Primes · Grades 6–8 · Unsolved

Twin Prime Conjecture

Primes that are just 2 apart, like 11 and 13, keep showing up forever.

Primes up to 100 are shaded. Twin pairs are orange. They get rarer, but do they ever stop?

Try it

3 and 517 and 1941 and 43

We’ve known for over 2,000 years that primes never run out.

Since 2013 we know primes keep coming within 246 of each other forever. Getting that down to 2 is the unsolved part.

Look at the number between each twin pair: 4, 6, 12, 18, 30… What do you notice?

Can three primes in a row be 2 apart, like 3, 5, 7? Ever again?

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