Vsauce2

Original Title: 2 Prime Numbers = Perfect Palindrome

We can't write out every digit of Pi every time we use it, but we've got to represent it somehow. And you were probably taught that 22/7 was a great option. Well... it's an okay option. It's not bad, but it's not amazing.

A handful of numbers have a very special property: you can add their digits together and divide the original number by their total without a remainder. And why does it matter? Well, in terms of mathematics, it's mostly a curiosity. Dattatreya Ramchandra (D. R.) Kaprekar saw these numbers as sparking joy in the mind, so he named them "Harshad" numbers, with harshad being the Sanskrit word for joy. And it's an important lesson about numbers: not every bit of math needs to change the world. Something that makes you go "huh" for a brief moment can be enough.

Original Title: The Most Annoying Kaprekar Number

Kristen Gilbert was nicknamed the “Angel of Death” because so many patients happened to die during her shifts. No one saw her doing anything wrong, and there just wasn’t any physical proof in post mortem examinations… but many of the patients who went into cardiac arrests didn’t have health problems that should result in heart failure. Some were even young and physically healthy. But without hard evidence, is it even possible to determine whether a doctor or nurse is actually killing patients?

As borders twist and turn through geographic features and political realities, maps get complex quickly. But no matter how many bodies are being mapped, it's only necessary to use 4 different colors to make sure that no two that are touching share the same color. Given how intricate and complicated maps can be, how can we not need more than 4?!

Imagine a world in which everything about your life -- your friends, your family, which school you went to, your social media activity -- are reduced to a simple number used by police and the government to determine whether something bad will happen to you. It sounds crazy, and almost paranoid, but algorithm-based initiatives have aided police from Chicago to London to help guide public safety interventions. In the case of Robert McDaniel, he was assigned a score that put him on Chicago’s “Heat List,” and he was told that he was likely to be involved in a shooting. But police didn’t know whether he’d be the shooter or the victim. That resulted in the city offering him a range of services, but it also put him on the police’s radar -- and that began a chain of events that fulfilled a grim prophecy. The promise of advanced math utilizing increasingly sophisticated data collection grows stronger by the year… but so do its potential perils. Can quantifying a person’s behavior actually te