What learning math can look like – arithmetic and factorials

Once in a while the way one of my kids solves a problem catches me by surprise. In today’s case I got an example of my younger son seeing a common math contest problem for the first time. When you’ve seen a problem 1,000 times you forgot what it is like to have not seen the problem previously.

I love his solution – especially because it shows how a kid can think about a pretty complicated problem involving numbers that you can’t really write down: