Our 100th episode! What's the big deal?

ISA CAMARGO: You're listening to Brains On where we're serious about being curious.

NARRATOR: Brains On is supported in part by a grant from the National Science Foundation.

MOLLY BLOOM: We did it. We made it to 100 episodes.

ISA CAMARGO: Awesome. What should we do to celebrate.

MOLLY BLOOM: Hmm, I'll light a firework that when it blows up, it spells out "seriously curious."

[FIREWORKS POPPING, CHEERING]

ISA CAMARGO: Whoa, beautiful. I'm going to get a giant cake, wheel it in here, and then have a dinosaur pop out.

[ROAR, SQUEAK]

MOLLY BLOOM: It's even got a hat on. Well, I'm going to have a dance party with 100 cats--

[MEOW]

--and 100 dogs.

[BARK]

And they're all going to get along.

ISA CAMARGO: Is that cat doing the robot? Awesome. Well, I'm going to celebrate by giving you this gift.

MOLLY BLOOM: Oh, thanks.

ISA CAMARGO: And inside it is 100 high fives.

[CLAPPING]

MOLLY BLOOM: Wow, that is so cool. There's so many of them.

ISA CAMARGO: One for every episode of Brains On.

MOLLY BLOOM: Well, this could take a while.

ISA CAMARGO: Keep listening.

[CLAPPING, MUSIC PLAYING]

MOLLY BLOOM: Whew! I think I have a callus on my hand from all those high fives. But man, I feel like a rock star after that. OK. You're listening to Brains On from American Public Media. I'm Molly Bloom. And my co-host today is Isa Camargo from Orlando, Florida. Hi, Isa.

ISA CAMARGO: Hi, Molly.

MOLLY BLOOM: So we've asked you to host this episode because you've sent us a lot of questions, not quite 100 questions but a lot. Do you remember any of them?

ISA CAMARGO: Well, I don't remember a lot of them because I sent so many. But I do remember three. What is the biggest constellation in the sky? Why do people use makeup? And is there really a point for pinkie toes?

MOLLY BLOOM: [LAUGHS] Those are all really, really good questions. So do you like being super curious, or is it sometimes frustrating?

ISA CAMARGO: Well, kind of both. I like being curious because I'm wondering like 24/7. But I don't like being curious because once I ask one question, I want to know another and another. And I think you get the point of like what I'm trying to say.

MOLLY BLOOM: I do.

[LAUGHING]

So do you know what you want to do when you grow up to put all of this amazing curiosity to use?

ISA CAMARGO: I've always wanted to be an astronomer because science and space is super cool and interesting.

MOLLY BLOOM: That is super cool. Is there a specific thing about space that is kind of your favorite thing to think about?

ISA CAMARGO: Black holes.

MOLLY BLOOM: Oh. What is your favorite fact about black holes?

ISA CAMARGO: How the gravitational pull is so strong, even light can't escape.

MOLLY BLOOM: Well, Isa, I think you are the perfect host for our 100th episode because we're going to focus all of our curiosity on just that.

ISA CAMARGO: The number 100, it's a pretty popular number.

MOLLY BLOOM: 100 pennies in a dollar.

ISA CAMARGO: 100 yards in a football field.

MOLLY BLOOM: There are 100 centimeters in a meter.

ISA CAMARGO: And 100 years in a century.

MOLLY BLOOM: When you give your all, it's 100%.

ISA CAMARGO: And water boils at 100 degrees Celsius.

MOLLY BLOOM: You see the number 100 everywhere, but why?

ISA CAMARGO: We called Rafael Nunez earlier this week to ask him.

MOLLY BLOOM: He's a cognitive scientist at University of California, San Diego.

RAFAEL NUNEZ: Isabella, OK. Hi, my name is Rafael.

ISA CAMARGO: Nice to meet you.

RAFAEL NUNEZ: Nice to meet you. Where are you?

ISA CAMARGO: I live in Orlando, Florida. And I'm in my dining room right now.

RAFAEL NUNEZ: Well, I'm on the other side of the US, in San Diego, California.

ISA CAMARGO: Oh, cool.

RAFAEL NUNEZ: Yeah, very cool.

ISA CAMARGO: Why do people think the number 100 is so important?

RAFAEL NUNEZ: Oh, OK. Well, can I ask you a question back to you? Who's people for you there?

ISA CAMARGO: Well, just basically like everyone at my school because they celebrate the 100th day of school a lot. And everyone's like, oh, happy 100th day of school. And I'm like, why are you so excited about the number 100?

RAFAEL NUNEZ: [LAUGHS] I see. Yeah, that's a good question. Well, you see, we, people, we, humans, we love to have milestones. We're very good at it. Many, many cultures, milestones of all sorts are marked with kind of important events, important parties, important celebrations, important rituals, and so.

ISA CAMARGO: What is a milestone?

RAFAEL NUNEZ: Yeah, that's a very good question. Thanks for asking me. So they used to be done on stone, on the side of the road, saying, OK, here is the mile 20 or whatever, so you know where you are. This is before GPS, before cell phones, and so on. So it was very important for people to get oriented.

So we use it metaphorically sometimes to say, some days are very important, like a birthday party or like some holidays or graduation day and so on. So those are kind of metaphorically now referred to milestones as when we talked originally in the past as marking some distance on the road when you were traveling from one place to another.

So in our Western culture, numbers are very important. We use them for everything, for money, for paying, for measuring time, for measuring temperature. And we talk about that all the time.

Sometimes we have milestones that involve numbers. So for example, the NFL, the Super Bowl 50, there was a huge, huge event, much bigger than the other Super Bowls because it was 50, 5-0. So then you say, well, why didn't they do that for this Super-- well, because it was 52. [CHUCKLES] It was a 50. It looks like an important milestone.

So then the question, well, what's in common between 50, in the case of the Super Bowl there, or 100? Well, they have in common that they sort of count in tens. Now, we may want to know why it's 10 important, right, or why is 5 important?

It may have to do a little bit with the fact that our anatomy-- you know, we are animals with upper limbs and lower limbs, so arms and legs. So each one has five toes or five fingers. So in the upper limbs, the hands, we have a total of 10 fingers.

So when we manipulate objects and when we imagine in the old times, in human evolution, people cooking or people preparing fire or doing, preparing tools, and so on, always manipulating objects with this 10 fingers in front of them.

And so it could be that this is in part of why we are so prone to gather things in groups of tens or groups of five. And actually, in English, the word "five" comes from fist, which is like five fingers in one hand. So it has kind of a very prominent presence, the five and the tens.

And then if you count groups of tens, in fives and tens, and you start to get 100s and 50s, and so on.

ISA CAMARGO: I know people think that the number 100 is important, but is the number 100 important?

RAFAEL NUNEZ: Well, as I was saying, it becomes important when we call it to be important, when marking the end, for example, of all those numbers that you write with in our system, at least, with two digits. You get to 98, so a 9 and an 8, and then 9 and a 9.

And then boom, you start like a new type of number, which now would have three digits, 1-0-0. And then you go 1-0-1, 1-0-2, 1-0-3, and so on. So these are, in a certain way, cultural picks based on the fact that we like to mark labels and milestones.

And also, we have a notation that supports that. It kind of makes it more visible that 100 is something qualitatively different from 99 and 101.

ISA CAMARGO: That's so cool. Do other cultures celebrate the number 100? If not, do they celebrate a different number like 1,000?

RAFAEL NUNEZ: Well, that's a very interesting question, too. So in other cultures, for example, they don't even have numbers around 10. 100 is the way we designate, very precisely, a certain type of quantity that in other cultures may be just something like many or a lot.

So many cultures just work like that that's all they need. Until not so long ago in human history, before some groups invented writing, probably, a lot of the quantities were just referred as that. So in that sense, the idea of 100 being precise and important, so on, didn't even exist.

ISA CAMARGO: Thank you.

RAFAEL NUNEZ: All right. Have a good time. Bye-bye. Thank you.

(SINGING) Ba ba ba ba ba ba ba ba ba ba brains on.

MOLLY BLOOM: When it comes to the number 100, there's a lot to wrap your head around.

ISA CAMARGO: That's something one of our old friends is learning the hard way.

MOLLY BLOOM: Let's hear about it. This is the Tale of Gangador Versus 100.

NARRATOR: Meet Gangador.

GANGADOR: Hello, it me, mightiest in land.

NARRATOR: He was trained from birth to battle monsters for a sport called most epic fighting battle round!

MONSTER MASTER: And he was so good too.

NARRATOR: That's Monster Master, Gangador's trainer. They were unstoppable until one fateful match against a sound wave.

GANGADOR: Hear the battle in Brains On piano episode.

NARRATOR: After Gangador's defeat, he decided to quit fighting and go back to school to study dance.

MONSTER MASTER: A ridiculous idea, if you ask me.

NARRATOR: But no one asked you. Now, Gangador is about to finish high school and apply for the dance program at Juilliard. But one thing stands in his way, math class.

[MUSIC PLAYING]

[SCHOOL BELL RINGS]

MS. BROWN: All right, class, see you tomorrow. Oh. Hey, uh, Gangador, do you got a minute?

GANGADOR: Gangador has all the minutes.

MS. BROWN: Yeah, great. OK, look. I know you've been trying, but your math grade is still too low for me to pass you this semester.

GANGADOR: But Gangador must pass. Gangador need diploma for college.

MS. BROWN: I know. I know this means a lot to you. So here's what I'm proposing. I'm going to give you a special extra credit assignment. And if you ace it and keep your grades up, I'll pass you. But if you fail, I'm sorry.

GANGADOR: Give Gangador a chance. Gangador will conquer extra credit, just like Gangador conquered Vomit Vixen and Dragon Face in many battles.

MS. BROWN: What's a vomit v-- you know what, I don't care. Here's your assignment. I want you to find a way to add up all the numbers between 1 and 100 in your head. No paper, no calculator. I'll give you two days to figure it out, and you tell me how you did it. Sound fair?

GANGADOR: Challenge accepted!

[MUSIC PLAYING]

MS. BROWN: Where'd that music come from?

GANGADOR: 1 plus 2 plus 3 is 6! Pow! 4 plus 5 is 9. Add 9 and 6 to get 15. 15 plus 7 and 8 is-- wait, did Gangador forget 6? Gangador confused. Starting over. 1 plus 2 is 3.

MS. BROWN: OK, OK, OK. Think on it, Gangador. You've got until Friday. Good luck.

GANGADOR: Thank you, mighty master of math.

MS. BROWN: Uh, It's Ms. Brown. And you're welcome.

GANGADOR: Now, add 14 and 15, and you get-- wait, did Gangador forget 13? Gah! Starting over. 1 plus 2 is 3.

KYLIE: Hey, Gangador. What's with the counting?

GANGADOR: Hi, Kylie. Gangador must add up all numbers between 1 and 100 in head to pass math.

KYLIE: Yikes, sounds tough.

GANGADOR: Yes, harder than doing double kick-karate chop-knee jab combo.

KYLIE: Uh, is that a fighting thing?

GANGADOR: Yeah. That life over now.

KYLIE: Well, I'm sure you'll solve that math problem. Oh, and look what I brought.

[BAG UNZIPPING]

It's our costumes for the Talent Show Friday. Check it out.

GANGADOR: Wow! Costume is perfect.

KYLIE: You don't think this is too many sequins, do you?

GANGADOR: Gangador needs all the sequins. Gangador dances to show world how Gangador feels inside. Shiny costume part of that.

KYLIE: Cool, I agree.

KEVIN: Hey, look. It's that weirdo Kylie with her freak friend Ganga-dork.

[LAUGHS]

STUDENT: Good one, Kevin.

GANGADOR: No, I'm Gangador, masher of faces, crusher of kidneys, defeater of the hordes of dog breath, and conqueror of the realm of blur.

KEVIN: you always talk like that? More like Ganga-bore.

STUDENT: Oh, snap.

KEVIN: Am I right? Up top.

[CLAPS]

STUDENT: Yeah, dude. What weirdos. [LAUGHS]

KEVIN: Come on, guys. Let's go write the word "butts" inside library books. Later, losers.

STUDENT: Smell you later.

KEVIN: Oh, man.

[LAUGHS]

KYLIE: Just ignore them, Gangador. They're insecure brats.

[BEEPS]

ANNOUNCER: Gangador, please report to the principal's office.

KYLIE: That's weird. Are you in trouble?

GANGADOR: No idea.

KYLIE: Well, I'll see you in English. Later.

[DOOR CREAKS]

ADMIN: Are you Gangador?

GANGADOR: Mightiest in land, yes.

ADMIN: This call is for you.

GANGADOR: Call? Who could it--

MONSTER MASTER: Hey, Gangy-old pal. It's me, your dear friend, the Monster Master. [CHUCKLES] You remember me, right? We used to fight other monsters together.

GANGADOR: Gangador remembers.

MONSTER MASTER: Sorry to interrupt your, uh, preschool or whatever.

GANGADOR: High school.

MONSTER MASTER: Sure, that. Anyway, I was calling to see if you're ready to come back and fight for me. Battles just aren't the same without you. None of my other monsters come close to your skill and strength.

GANGADOR: Gangador done fighting. Students now and soon world famous dancer.

MONSTER MASTER: Dancing? What a Ganga-snore. You are meant for epic battles and beating the pulp out of your enemies. Dancing is for graceful creatures.

GANGADOR: Gangador is graceful.

MONSTER MASTER: Yeah, right. You'll see, you are born to fight. You can't escape it. You'll fail at dancing. You'll fail at school. And then you'll come begging me to take you back. [CHUCKLES] You'll see. You'll see.

GANGADOR: No!

[RECEIVER DROPS]

Monster Master is wrong. Gangador can dance. Gangador can graduate. Gangador just needs to solve math problem.

ADMIN: Are you done?

GANGADOR: Yes.

ADMIN: Then chop-chop with the pep talk and get to class.

GANGADOR: Sorry.

[MUSIC PLAYING]

[WHISTLE BLOWS]

INSTRUCTOR: Five more laps, people and uh, whatever you are, Gangador.

GANGADOR: OK. What if Gangador starts at 100 and adds backwards? 100 plus 99 is 199. 199 plus 98 is-- why is problem so hard?

KEVIN: Hey, look, dummy-dor.

GANGADOR: Not now, Kevin. Gangador trying to concentrate.

KEVIN: On what, not tripping over your giant feet while you run? [CHUCKLES] Good luck.

GANGADOR: No, concentrate on math.

KEVIN: Here's a problem for you. What do you get when you take away 100 from 100?

GANGADOR: Uh, zero?

KEVIN: What a coincidence. That's like your IQ, right? [CHUCKLES]

GANGADOR: Uh, Gangador not need this now. Gangador toss Kevin.

KEVIN: What? Let go of me, you freak. [CRIES]

GANGADOR: Kevin go bye-bye.

KEVIN: Please don't throw me. I'm sorry I'm such a jerk. Raging hormones combined with unresolved childhood issues make me insufferable. Wah!

[WHISTLE BLOWS]

INSTRUCTOR: Gangador, put Kevin down. You just got detention, buddy.

GANGADOR: Oh, no.

[SCHOOL BELL RINGS]

KYLIE: Hi, Gangador. Why is your tray empty? Are you not eating?

GANGADOR: Gangador almost toss Kevin. Have detention today. Feeling bad. Not hungry.

KYLIE: Sorry, pal. But he probably deserved it. Look, we can always move our dance rehearsal to later this evening when you get out.

GANGADOR: Maybe Gangador skip rehearsal.

KYLIE: But the talent show is tomorrow. We need to polish our leaps and high kicks.

GANGADOR: What is point? Gangador cancel 100 problem. Gangador going to fail math. Gangador is dumb. And not graceful just like Kevin and Monster Master say.

KYLIE: No, you're not-- traditionally graceful. But no one moves like you.

GANGADOR: Forget it. Gangador done with school. Done with dancing. [CRIES] Gangador is just dumb fighter. Goodbye, Kylie!

KYLIE: Don't say that. I don't want to dance without you. Gangador, come back. Gangador! Gangador!

NARRATOR: Will Kylie and Gangador get to show off their sequins at the talent show? Will Gangador solve his math problem? Will Kevin and Monster Master ever grow up? Keep listening.

ISA CAMARGO: Wow, what a cliffhanger.

MOLLY BLOOM: I know. We are going to hear how it all turns out in just a bit. But first, 100 episodes means we've all learned a lot of cool stuff.

ISA CAMARGO: But some facts are just cooler than others.

MOLLY BLOOM: We asked you to tell us about your favorite fact from the show, and here's what you said.

[MUSIC PLAYING]

AUDREY: My favorite fact that I learned on Brains On is if you connected all the nanotubes, you could put in elevator, and it could go into space.

LIBBY: Astronauts eat dried up food.

DREW: Dogs can smell how high or low a human's blood sugar is.

EVIE: The dogs can smell pee in the pool.

DREW: When dogs sniff each other, they can tell how each other are feeling.

EVIE: How dogs can tell how other dogs are feeling but just by smelling.

ELOISE: My favorite fact that I learned on Brains On is that dolphins throw octopuses into the air so that they can eat them. So their suckers don't choke the dolphins.

DONOVAN: Taller elevators go faster than shorter elevators.

KALE: The one I want the-- about a tornado. Some can go up to the clouds, and some go down from the cloud.

JACOB: One fact I learned was how they make dead people twitch with electricity.

LILI: I like learning how lasers work. They're really cool.

DOROTHY: Turtles or tortoises can live for 100 years.

MOLLY BLOOM: That was Emerson, Audrey, Libby, Drew, Evie, Eloise, Donovan, Kale, Lili, Jacob, Dorothy, and Elliot. Isabella, do you have a favorite fact from Brains On?

ISA CAMARGO: My favorite fact was when I learned that there were three types of tears, basal tears, reflux tears, and emotional tears.

MOLLY BLOOM: So why did that fact stick out to you?

ISA CAMARGO: Because I thought there's only one type of tear, that was the emotional tear, but then I found out there are two others. And I was like, what? Two other tears?

MOLLY BLOOM: So it surprised you.

ISA CAMARGO: Mm-hmm.

MOLLY BLOOM: Well, I have a fact and a surprise right now because it's time for the mystery sound.

[MUSIC PLAYING]

ISA CAMARGO: (QUIETLY) Mystery sound.

MOLLY BLOOM: Ears open, brains on. Here we go.

[HUMMING, CLICKING, WHIRRING]

OK, do you have a guess?

ISA CAMARGO: It sounds like someone running in like this big stadium, sort of. [CHUCKLES]

MOLLY BLOOM: That is an excellent guess. We are going to let you think on it just a little bit more. And we'll be back with the answer very soon.

[MUSIC PLAYING]

ISA CAMARGO: Do you have a mystery sound to share or like me, a lot of questions you'd love answered?

MOLLY BLOOM: Do not be shy. Send them to us at hello@brainson.org. That's how we got this head scratcher.

ROSEMARY: Hi, my name is Rosemary, and I'm from Dallas, Texas.

XANDER WAGNER: My name is Xander Wagner. I'm from Phoenix, Arizona. And my question is--

BOTH: Why does your stomach rumble when you're hungry?

ISA CAMARGO: We'll answer that in our Moment of Um at the end of the show.

MOLLY BLOOM: Plus you'll hear the latest group of awesome honor roll members. You too can get on that list by sending us a question or a drawing.

ISA CAMARGO: Like maybe a drawing of our fireworks, dyno cake, dog and cat party?

MOLLY BLOOM: I can't even. If someone drew that, my head would explode with joy.

ISA CAMARGO: There's your challenge, listeners. Make Molly's head explode with joy by drawing that party. [LAUGHS]

MOLLY BLOOM: The dinosaur was wearing a tiny hat. Please, someone draw me a dinosaur in a tiny hat.

[MUSIC PLAYING]

This is the 100th episode of Brains On. I'm Molly Bloom.

ISA CAMARGO: And I'm Isa Camargo.

MOLLY BLOOM: And we're talking all things 100.

ISA CAMARGO: You might think you know the number 100, but it's got some tricks up its sleeve.

MOLLY BLOOM: If numbers had sleeves.

ISA CAMARGO: Here to show us some cool 100 tricks is Arthur Benjamin.

MOLLY BLOOM: He's a mathematician and a professor of mathematics at Harvey Mudd College. Hello, Arthur.

ARTHUR BENJAMIN: Hello.

MOLLY BLOOM: We are very excited to have you here. So tell us why the number 100 is so magical.

ARTHUR BENJAMIN: Well, I'm a mathematician, and the number 100 is very interesting for several reasons. For example, 100 is a perfect square. 10 squared is 100. And the reason it's called squared is if you took 10 rows of dots and laid them in a row, 10, 10, 10, 10-- in 10 rows, then you form a square. And that's 100.

I like multiplying numbers, squaring numbers, cubing numbers. If you take the cubes of the numbers 1, 2, 3, and 4, right, 1 cubed is 1, 2 cubed is 8, 3 cubed is 27, 4 cubed is 64. If you add them together, guess what, you get 100.

MOLLY BLOOM: What?

ISA CAMARGO: [GASPS]

ARTHUR BENJAMIN: So that's pretty cool. But let me show you something even more magical, something that I want you and all your listeners to do. I want you to think of a number between 1 and 10. Don't tell me what it is, just think of it.

MOLLY BLOOM: OK.

ISA CAMARGO: Got mine.

ARTHUR BENJAMIN: OK, now double that number.

MOLLY BLOOM: Mm-hmm.

ARTHUR BENJAMIN: OK.

ISA CAMARGO: Mm-hmm.

ARTHUR BENJAMIN: Now, let's add 10 to that number.

MOLLY BLOOM: OK.

ISA CAMARGO: OK.

ARTHUR BENJAMIN: Now, whatever you're thinking of, I want you to divide it by 2. That's the hard part.

MOLLY BLOOM: Mm-hmm.

ARTHUR BENJAMIN: OK? You got it, Isa?

ISA CAMARGO: Um, I think I got it.

ARTHUR BENJAMIN: OK, now, I want you to subtract the number that you started with. Now, whatever you're thinking of, I want you to double that number.

MOLLY BLOOM: Mm-hmm.

ARTHUR BENJAMIN: And now, I want you to multiply that number by itself. And if the magic has been working, you should be thinking of the number 100 now.

MOLLY BLOOM: Yes.

ISA CAMARGO: That's so cool.

ARTHUR BENJAMIN: Here's another one that's also pretty mysterious. Think of a number between 1 and 50, OK? Think of it, make it a two-digit number between 10 and 50.

MOLLY BLOOM: OK.

ARTHUR BENJAMIN: OK?

ISA CAMARGO: OK.

ARTHUR BENJAMIN: So whatever number you're thinking of, I want you to add the digits together. So like if you were thinking of 42, then 4 plus 2 is 6. But don't tell me what it is. Now, I want you to subtract that number from the two-digit number you started with.

So for example, if you start with 42, you'd subtract 6, and now you'd have 36. OK?

MOLLY BLOOM: Mm-hmm.

ARTHUR BENJAMIN: Now, whatever number you're thinking of now, I want you to add those numbers together. If you're thinking of 34, then 3 plus 4 is 7. That's all I'm saying.

MOLLY BLOOM: Got it. Got it.

ARTHUR BENJAMIN: If you have a one-digit number, leave it alone. If it's a two-digit number, add those two digits together, OK?

MOLLY BLOOM: Mm-hmm.

ISA CAMARGO: OK.

ARTHUR BENJAMIN: Now, I want you to add 1 to that number. That's easy. All right. And if we multiply that number by itself, I'll bet we get 100 again.

MOLLY BLOOM: Yes.

ISA CAMARGO: We do. [LAUGHS]

ARTHUR BENJAMIN: Yay.

ISA CAMARGO: So I know that you said like the problem you do will always equal 100. What if you do a number that's above 100? Will it still equal 100?

ARTHUR BENJAMIN: It absolutely will. Whether we started with 6 or 50 or a million or a googol-- by the way, do you know what a googol is? It's the number 1--

ISA CAMARGO: It's a website?

ARTHUR BENJAMIN: --with a hun-- no. It's a 1 with 100 zeros after it. So it's a gigantic number. Googol and the company Google was kind of named after that giant number. And if you put a 1 with a googol number of zeros after it, that's called a googolplex.

I don't know any applications for a googolplex. But it's still cool that you can think of these numbers even if you'd never be able to write it down even if you spent your whole life writing down numbers. So that's pretty cool.

MOLLY BLOOM: So cool. Well, thank you so much for sharing your amazing math with us.

ARTHUR BENJAMIN: My pleasure. See you later.

ISA CAMARGO: That was awesome. Bye.

(SINGING) Ba ba ba ba ba ba ba ba ba ba ba brains on.

MOLLY BLOOM: Hmm. I wonder if any of those tricks could help Gangador with his math problem.

ISA CAMARGO: Let's find out. Let's get back to the Tale of Gangador Versus 100.

NARRATOR: When we last left Gangador, he was struggling in math and trouble at school and just blew off his best friend. Geez. This story is depressing. Let's rejoin the story later that night.

GANGADOR: Gangador is failure! All Gangador good for is smashing. Stupid school. Stupid boys. Stupid math problem. Gangador is so mad! [GROWLS] Want to break number 100 apart!

NARRATOR: Well, that's an idea.

GANGADOR: Who said?

NARRATOR: Never mind, though. What were you just saying?

GANGADOR: That, uh, Gangador wants to break 100?

NARRATOR: Interesting. What would happen if you broke it apart?

GANGADOR: Well 100 becomes two parts. One starting at 1, and the other ending at 100.

NARRATOR: Hmm. Say, what would happen if you took those two ends and started your adding their?

GANGADOR: Huh? Like adding the first number and last number? 100 plus 1?

NARRATOR: Sure, why not?

GANGADOR: It equal 101.

NARRATOR: 101. Well, what about the next two numbers you've got there?

GANGADOR: 99 and 2? Let's see. Also equals 101.

NARRATOR: Wow, now that's uncanny. Just keep going.

GANGADOR: Next is 98 and 3. Also 101. Then 97 and 4, 101 again. 96 and 5, also 101. They all equal 101.

NARRATOR: Fascinating. Each pair, when added, equals 101. But how many pairs are there total, I wonder?

GANGADOR: Easy. Pairs are sets of two. 100 divided by 2 equals 50. There are 50 pairs, all equal 101 when added together.

NARRATOR: OK. So you're telling me, you have 50 pairs of numbers in the number 100. And each one, when added together equals 101? Hmm.

GANGADOR: That means there is 50 pairs of 101. Answer to question is just 50 times 101.

NARRATOR: So what's 100 times 50?

GANGADOR: Fifty 100's. Easy. 5,000.

NARRATOR: And then what's 1 times 50?

GANGADOR: Just 50.

NARRATOR: So what is 101 times 50?

GANGADOR: 5,050.

[MUSIC PLAYS]

Wait, that answer, 5,050, that is what all numbers from 1 to 100 added up equal. Gangador gets it. Thank you, mystery voice for helping Gangador solve most vexing problem.

NARRATOR: I didn't help you. You figure it out all by yourself. In fact, I'm not really even here. This was all a dream. Dream. Dream.

[DREAMING MUSIC]

[ALARM CLOCK BEEPING]

GANGADOR: Ah! What weird dream. But Gangador has answer now. Gangador can pass math. Oh, no, late for school.

[ROCK MUSIC]

[SCHOOL BELL RINGS]

MS. BROWN: All right, class dismissed. Have a good weekend. And don't forget, next period is the talent show, so go straight to the auditorium.

GANGADOR: Math master, Gangador conquer problem. Have answer.

MS. BROWN: Great. Lay it on me.

GANGADOR: Gangador realized first number of 100 plus last number equals 101. Next highest and lowest numbers also equal 101. All pairs from there on, equal 101. There are 50 pairs of 101 total. 101 times 50 equal 5,050. Kapow! Gangador win.

MS. BROWN: Excellent work, Gangador. I'm proud of you. That wasn't easy.

GANGADOR: Gangador stomped off problems.

MS. BROWN: Well, I'm off to the auditorium for the talent show.

GANGADOR: Oh, no! Talent show. Gangador forgot. Time for epic run through halls.

MS. BROWN: Nope. No running allowed.

GANGADOR: Time for epic fast walk through halls.

MS. BROWN: You know what, I'll allow it.

[LIVELY MUSIC]

GANGADOR: Must get to stage in time. Must find Kylie.

NARRATOR: Meanwhile, backstage of the auditorium--

COORDINATOR: All right, Kylie. You're up in one minute. Ready?

KYLIE: No, I-- I can't do it. I'll look dumb. I'm-- [SIGHS] I'm just going to skip it. Is that OK?

GANGADOR: No, not OK! Kylie is meant to dance and so is Gangador.

KYLIE: Gangador, you made it.

GANGADOR: Gangador learn that dreams are important. Sometimes they help you solve math problems, and sometimes they tell you to dance.

KYLIE: I knew you wouldn't give up on yourself. But I don't think you have enough time to change into your costume.

GANGADOR: Gangador doesn't need costume. Gangador sparkles from inside. Now, let's show our big dance moves.

COORDINATOR: You guys are up.

KYLIE: All right, Gangador. Let's rock.

[APPLAUSE]

[MUSIC PLAYING]

GANGADOR: Hoo! Ha!

KYLIE: High kick, twirl.

GANGADOR: Sashay!

KYLIE: Pirouette, super pirouette.

GANGADOR: High kick!

KYLIE: Sashay. Jump twirl.

GANGADOR: Ah!

[CHEERING]

MOLLY BLOOM: Hey, Isa, are you ready to hear that mystery sound again?

ISA CAMARGO: Yes, I am.

MOLLY BLOOM: Here it is.

[HUMMING, CLICKING, WHIRRING]

OK, any new thoughts?

ISA CAMARGO: I mean, it's so sounds like someone running. But I'm changing like where they're running. Instead of like a big stadium, I think they're like at the gym or something.

MOLLY BLOOM: That's an excellent guess. Here's the answer.

HANNAH SONSALLA: That was the sound of me sprinting the 100-meter dash.

MOLLY BLOOM: So Isa, you were 100% correct.

ISA CAMARGO: Yeah. [CHUCKLES]

MOLLY BLOOM: That's Hannah Sonsalla. She's a computer science and math major at Macalester College. And she also holds the school's record for the 100-meter dash, just 12.26 seconds.

ISA CAMARGO: Cool.

HANNAH SONSALLA: I began sprinting in like sixth grade. So I've been running for about 8 to 10 years, I'd say. My first sport was basketball. And for that, yeah, going back and forth on the court, there's a lot of movement. And you have to be really quick to be able to get back on defense or get back on offense.

So I'd say I'd always have-- like be fairly quick. But when you do a sport that's like purely running, it helps you to focus a lot more on that speed.

MOLLY BLOOM: So there's a lot that goes into running 100 meters in 12.26 seconds. During practice, Hannah and her coaches pay extremely close attention to each step she's going to take. Every movement from head to toe is scrutinized and refined. So when race day comes, she doesn't even have to think about what her body is doing.

Hannah thinks about the race in three parts.

HANNAH SONSALLA: Mentally, at the beginning of the race, right when you get out of the blocks, I'm really focused on just pushing hard, trying to push the track behind me, and get out very quickly. And then the middle of the race is more running as fast as you can, so you're accelerating from the beginning through the middle.

And then the last part, I'm just trying to make it to the finish line before anybody else or as fast as I possibly can.

MOLLY BLOOM: Isa, do you run?

ISA CAMARGO: I used to be in Runner's Club. But I don't anymore because it only lasted for like two weeks. And I'm like, I can't do this anymore. I'm just not meant for running.

[LAUGHING]

I quit.

MOLLY BLOOM: I feel the same way. I am not a runner. But for those who are runners in our audience, if you want to go a little faster in your next race, Hannah has something you can practice.

HANNAH SONSALLA: For sprinters, I would say, make sure you're running on your toes. Don't be a heel striker. So when you run on your toes instead of strike your heels first, you're touching the ground a lot less. Your feet are in the air a lot more, and that allows you to have a faster reaction. And then you're running faster.

So I think running is just something that everybody can do. And I don't think there's really a right or wrong way to do it. There might be a more efficient way to do it, but it's not really wrong.

MOLLY BLOOM: OK, listeners. On your mark, get set, go.

[MUSIC PLAYING]

Before we go, we have a gift for you, our listeners.

ISA CAMARGO: There's no way we could have made it this far without all our friends, fans, and family.

MOLLY BLOOM: So our producer Marc Sanchez wrote this song.

[MUSIC PLAYING]

(SINGING) Thank you and you and you and you and you and you. Thank you and you and you and you and you and you. Thank you and you and you and you and you and you. Thank you and you and you and you and especially you.

SANDEN TOTTEN: Hey, this is Sanden. Thank you. Thank you. Thank you. Thank you. Oh, man, 100 episodes, what an achievement. Couldn't have done it without you. That's right, without you. You're awesome Thank you.

MARC SANCHEZ: Hey, everybody, this is Marc. And I just wanted to say that you did it. Not we did it, you did it. You helped us get to 100 episodes. Here's to another 100.

MOLLY BLOOM: This is Molly. And I just want to say it's been so much fun making these episodes. And we want to thank you for listening to them and sharing your ideas and questions and mystery sounds and all of the awesome things that you send us that make this show possible.

Thank you. 100, more like fun-hundred.

(SINGING) Da-ra-rap. Da-ra-rap. Da-ra-rap-dap-da-rap-da. Thank you and you and you and you and you and you. Oh, thank you and you and you and you and, of course, you too. Da-ra-rap. Da-ra-rap. Da-ra-rap-dap-da-rap-da. Da-ra-rap. Da-ra-rap. Da-ra-rap-dap-da-rap-da.

ISA CAMARGO: In many cultures, the number 100 is everywhere.

MOLLY BLOOM: That's because these cultures count in a system known as base 10.

ISA CAMARGO: It probably stems from the fact that we have 10 fingers.

MOLLY BLOOM: But not every culture cares about the number 100, and some don't even have precise numbers like that at all.

ISA CAMARGO: And the number 100 has some pretty cool math around it, especially if you can remember all those cool tricks we learned. That's it for episode 100.

MOLLY BLOOM: Yes, we did it. High five!

[CLAPS]

Ow, still a little sore their.

ISA CAMARGO: Brains On is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.

MOLLY BLOOM: We had engineering help from Michael DeMarc, Veronica Rodriguez, and Mac Doula.

ISA CAMARGO: We had production help from Emily Allen, Jon Lambert, Lauren Dy, and Jacqueline Kim.

MOLLY BLOOM: Special Thanks to Jill Ferris, Judy Augsburger, John Miller, Nancy Yang, Abby Stevens, Ali Losaf, Chris Worthington, Diana Floaton, and Max Nestra.

ISA CAMARGO: You can follow us on Twitter and Instagram. We're @brains_on. And find us on Facebook too.

MOLLY BLOOM: Oh, and we would love if you told a friend about the show. It is the best way for us to grow.

ISA CAMARGO: Now, before we wrap it up, it's time for the Moment of Um.

[THEME PLAYING]

Um, um, um, um.

Why does your stomach rumble when you're hungry?

LILY DARA: Hi, I'm Lily Dara. I am a gastroenterologist and an assistant professor of medicine at the University of Southern California in Los Angeles.

[STOMACH RUMBLING]

Gastroenterologist is a doctor that treats people who have a stomach and bowel and liver and pancreas disorders. So basically, if you have a tummy ache or if you have diarrhea or liver disease, then you'd come to a gastroenterologist.

So to start off, you have to understand what the GI system, the stomach and the intestines do. Basically, their job is to get all the good stuff out of food, what we call nutrients, so that we can grow stronger, and we can remain healthy.

In order to do that, once you eat the food, the stomach and the intestines have to move around and squeeze the food and turn it into smaller pieces.

Imagine you're holding a cracker in the palm of your hand. And when you make a fist, you squeeze your hand muscles to break that cracker into pieces. The stomach is basically like a balloon made up of muscles. And that's what it does.

When you eat, it squeezes, and it breaks up the food into smaller pieces. When you're not eating, the stomach is still squeezing, it's still moving. And it has the liquids necessary to digest the food inside. But instead of food, it's filled with air. So what ends up happening is that you make bubbles.

And the bubbles make gurgling noises. And that's basically why our stomachs, our intestines make noises, is the air and the liquids moving through empty hollow spaces.

[TODDLER GIGGLING]

It's just the natural movement of your bowels and your stomach. And there's nothing to be ashamed of. That's absolutely natural and normal.

Um, um, um.

MOLLY BLOOM: I never grumble over having to read this list. It's the latest group to join the Brain's Honor Roll. These are the people who send us drawings, mystery sounds, and questions. Here we go.

[LISTING HONOR ROLL]

[MUSIC PLAYING]

We'll be back soon to answer more of your questions.

ISA CAMARGO: Thanks for listening.