BusyBeaver(6) Is Quite Large

> Also, the left-superscript means tetration, or iterated exponentiation: for example, 1510 means 10 to the 10 to the 10 and so on 15 times.

I thought it was a typo. First time I encounter tetration.

Continuing the theme of iteration: it was the first time I encountered pentation

One of the reasons I like the use of the number line in schools is that on the line it's more obvious when you're shown addition and multiplication and then later exponeniation that this is a pattern. With the number line, two natural questions arise and, hopefully by the time you're taught exponentiation the Math teacher knows enough math to confidently affirm the answer to both. Yes, it keeps going like this forever, that's called Hyperoperation. And yes, we did (probably) skip one, it's known as Successor-of and you were probably not explicitly shown this operator but it's the near end of that infinite succession.

When arithmetic is introduced just as a way to, for example, count money, it's more directly practical in the moment, but you're not seeing the larger pattern.

Don't forget identity. Its range is small but important!