ELI5: Explain Like I'm 5

Additive persistence

Additive persistence is a fun math game where you keep adding up the digits in a number until you get a single digit. It's like playing a game of "keep adding until you can't add any more!"

To play the game, you start with a number, like 57. You add up the digits in the number: 5 + 7 = 12. Now, you do it again: 1 + 2 = 3. You now have a single digit, so you're done.

But that's not all! Additive persistence is also a way to find out how many times you need to do this game until you get a single digit. For example, if you start with the number 57, you had to do the game two times until you got to a single digit. So the additive persistence of 57 is 2.

The really cool thing is that you can play this game with any number, and you'll always end up with a single digit. And every number has an additive persistence, which is the number of times you have to play the game to get to that single digit.

So, if you want to find out the additive persistence of a number like 1234, you would play the game until you get a single digit: 1 + 2 + 3 + 4 = 10, and then 1 + 0 = 1! You only had to play the game two times to get to a single digit, so the additive persistence of 1234 is 2.

In the end, additive persistence is just a fun math game that teaches us about the patterns in numbers and how we can break them down into smaller parts. So, grab a calculator and give it a try!