Our All About Me by Number worksheet gives kids a chance to exercise various skills as they focus on the numbers that ...

Say you want to count all the rough primes between 1 and 200. First, consider a handful of the smallest primes—like 2, 3, 5, and 7. Then list all the numbers that aren’t divisible by those primes.

They realized they could solve a slightly weaker version of their problem — one where the numbers getting squared only had to be “roughly” prime. Rough primes are much easier to find than primes. Say ...