Learn about the Luhn algorithm (the genius math behind credit card numbers) and how parents’ brains synchronize when they’re together. Then, play along at home and test your podcast knowledge with this month’s Curiosity Challenge trivia game.
Learn about the Luhn algorithm (the genius math behind credit card numbers) and how parents’ brains synchronize when they’re together. Then, play along at home and test your podcast knowledge with this month’s Curiosity Challenge trivia game.
The genius math behind credit card numbers by Cameron Duke
Parents' brains sync when they're together by Steffie Drucker
Episodes referenced in Curiosity Challenge Trivia with Kyann
Subscribe to Curiosity Daily to learn something new every day with Cody Gough and Ashley Hamer. You can also listen to our podcast as part of your Alexa Flash Briefing; Amazon smart speakers users, click/tap “enable” here: https://www.amazon.com/Curiosity-com-Curiosity-Daily-from/dp/B07CP17DJY
Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/parents-brains-sync-when-theyre-together-the-genius-math-behind-credit-card-numbers-and-julys-curiosity-challenge-trivia
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about the genius math behind credit card numbers; and how parents’ brains synchronize when they’re together. Then, play along at home and test your podcast knowledge with this month’s Curiosity Challenge trivia game.
CODY: Let’s satisfy some curiosity.
When you shop online and enter your credit card number, have you ever noticed that one wrong digit is enough for the card to be marked invalid? Have you ever wondered why? I mean, there are more than a billion credit cards in the world. Why doesn’t a mistake just charge someone else’s card?
CODY: Right, and like… a credit card can be instantly rejected even if there’s no internet connection, right? [ad lib]
ASHLEY: So it turns out that credit card numbers work so well thanks to some really cool math.
It all comes down to the very last digit, called the check digit. It can tell you if a credit card number has been typed wrong, or if it’s even real. It’s determined by a math formula called the Luhn [LOON] algorithm, otherwise known as the Modulo-10 algorithm. It works like this. (Fair warning, this gets a little complicated.)
That final check digit is determined mathematically by all the digits that come before it. To calculate it, the first step is to double every other digit, starting with the one right next to the check digit and moving to the left. If that math ever gives a double-digit number, you add the two digits together. So like, 2 times 4 is a single digit: 8. But 2 times 6 is two digits: 12. Those digits added together end up as 3. Once you’ve replaced those, you just add up the first 15 digits of the card number. The check digit will be the number you need to add to make the result divisible by ten. (I TOLD you this gets a little complicated!) So, if all of the digits add up to 81, you need to add 9 to get 90, so the check digit will be a 9. If the sum were 90 outright, the check digit would be a zero.
When you type in a credit card number, the computer does all of this math super quickly. If you make a mistake, the check digit will disagree with the math and the computer will instantly know you made a mistake. Now, it’s not failsafe: there’s a 1 in 10 chance that a random number will have the right check digit. But it will always catch a single mistyped digit, and almost always catch a pair of swapped numbers. And those are the most ways people get credit card numbers wrong.
This algorithm is embedded in tons of important numbers, not just on credit cards. You can find it in vehicle identification numbers, barcodes, book ISBN numbers, and even some countries’ social security numbers. Computer scientists even use something like this to identify when data has been garbled in transmission.
So that number on your credit card? It’s a lot smarter than you probably thought.
With lots of workplaces still closed due to the pandemic, some families are spending more time together than ever. And this has proven particularly challenging for parents. But new research is showing just how much co-parents can depend on each other. Their brains actually sync up when they’re together.
For this study, scientists from a university in Singapore recruited 24 heterosexual couples with kids aged 4 or younger. The couples first filled out a questionnaire to give the scientists a sense of how often each parent usually took the lead with childcare.
Next, they outfitted each participant with a headband full of sensors that measured activity in the prefrontal cortex. That’s a region of the brain responsible for executive function — stuff like self-control, motivation, and planning. The couples either sat in the same room together or in separate rooms, while the researchers played them a series of sound clips: a baby crying; a baby laughing; an adult crying; an adult laughing; and static, as a control sound.
Next, the researchers analyzed the couples’ brain activity. They found that activity in the prefrontal cortex actually synced up when the couple was in the room together. Importantly, that wasn’t true when they ran the same experiment with randomly matched strangers. The researchers say synchrony in this area of the brain suggests that parents are especially attuned to each other’s emotions, behavior, and point of view when they’re in the same room together.
But when they dug into the details, it got even more interesting. For one thing, their brains were only synchronized for positive or neutral sound clips, like a laughing baby or static — not for negative sounds like crying. That might sound like a problem, but the researchers say that’s actually not a bad thing. Past research has shown couples who have greater brain synchrony during stressful situations fight more often.
In this study, brain synchrony was also greater among younger, first-time parents, which suggests that parents probably get more independent and self-sufficient with experience. Synchrony was also greater in couples where the mom took the lead in parenting. Studies show mothers are more likely to solve conflicts through mediation, while fathers tend to solve them by asserting their authority. When mothers take the lead, then, it makes sense that they’d try to coordinate their response with that of their partner. And that would show up as synchronized brain activity.
So this study proves that parenting really is a team sport! So, parents, next time you’re feeling overwhelmed, turn to your partner. When it comes to raising kids, you can literally put your heads together.
ASHLEY: Today’s episode is sponsored by KiwiCo. KiwiCo creates super cool hands-on projects designed to expose kids to concepts in science, technology, engineering, art and design, and math — also known as STEAM. All from the comfort of home!
CODY: Each line caters to different age groups and there are a variety of topics to choose from. And every crate is designed by experts and tested by kids, and teaches a new STEAM concept. ASHLEY: If you’re listening to this podcast with your partner right now, then I’m sure your brains are already syncing up, thinking about how these projects can enrich your kids’ lives. I mean, they’ll structure, fun, AND opportunities for hands-on exploration at home. Not too shabby!
CODY: With KiwiCo’s hands-on art and science projects, kids can engineer a walking robot, blast off a bottle rocket, explore colorful, kid-friendly chemistry, and a whole lot more — all from the comfort of home.
ASHLEY: They have everything you need to make STEAM seriously fun — delivered to your doorstep. Get your first month FREE on select crates at kiwico-dot-com-slash-CURIOSITY.
CODY: That’s K-I-W-I-C-O dot com slash CURIOSITY
It’s time once again for the Curiosity Challenge! Every month, I call up a listener and put them to the test by asking three questions from stories we ran on Curiosity Daily in the previous month. For this Curiosity Challenge, I talked to Kyann, who’s an educator and Curiosity Daily listener in Phoenix Arizona. Let’s get started!
Nailed it! I’m so impressed. How did YOU do? If you’d like to play next month, OR if you have a question you’d like us to answer on the show, shoot us an email at podcast at curiosity dot com, or leave us a voicemail at 312-596-5208!
Leave us a voicemail at 312-596-5208!
CODY: Before we recap what we learned today, here’s a sneak peek at what you’ll hear next week on Curiosity Daily.
ASHLEY: Next week, you’ll learn about why moths are drawn to lights;
The complicated way interstellar travel can mess with language;
How we may be able to fight climate change with rocks;
And more!
CODY: Wait a minute. isn't there something else we'll learn about? I feel like next week is special for some reason… wait, I know. Can I cue the dramatic music? Cause I’m gonna cue the dramatic music. Because it's… [dramatic music] SHARK WEEK!"
ASHLEY: That’s right! Next week, we’re gonna DIVE IN to a different shark-themed topic every day. Can sharks really smell a drop of blood from a mile away? Why did the US military try to develop shark repellent during World War II? And what happened when our friend Forrest Galante, host of “Extinct or Alive” on Animal Planet, went looking for missing shark species off the coast of South Africa?
CODY: Stay tuned next week for our special Shark Week coverage, along with the variety of topics you’ve come to know and love from Curiosity Daily. [OPTIONAL: ...and, of course, dramatic music climaxes, like this!] [end dramatic music]
CODY: And NOW, let’s recap what we learned today.
[ad lib optional]
CODY: Today’s stories were written by Cameron Duke and Steffie Drucker, and edited by Ashley Hamer, who’s the managing editor for Curiosity Daily.
ASHLEY: Today’s episode was produced and edited by Cody Gough.
CODY: Have a great weekend, memorize your credit card number, and join us again Monday… for SHARK WEEK! to learn something new in just a few minutes.
ASHLEY: And until then, stay curious!