Suzy Scudder, a retired elementary school teacher, is trying help young students expand their counting skills.

The primes—numbers that are only divisible by themselves and 1—are the most fundamental building blocks in math. They’re also the most mysterious. At first glance, they seem to be scattered ...

A new proof has brought mathematicians one step closer to understanding the hidden order of those “atoms of arithmetic,” the prime numbers. The primes — numbers that are only divisible by themselves ...