Primes · Grades 6–8 · Unsolved

Goldbach's Conjecture

Every even number bigger than 2 can be made by adding two primes.

Each dot is an even number and how many ways it splits into two primes. The count keeps growing, and never hits zero.

Try it

10 = 3 + 728 = 11 + 17100 works six different ways

Goldbach wrote it in a letter to Euler in 1742.

Computers have checked even numbers into the billions of billions. Every one works, but checking isn’t proving.

Which even numbers can be made the most ways?

Why do we only ask about even numbers?

Detailed one-pager (PDF) History, why it’s unsolved, and more classroom ideas