Solution

159535

Problem
Two Primes Make One Square Back to problem
First name
Arnie Sykes
School
Norwich Lower School
Country
England
Age
9

I figured out that all the odd square numbers (apart from 121 and 289) up to 400 can only be made if you add 2 to the first prime number before it. So I did that for all the odd square numbers apart from 121 and 289. Then I just figured out the rest of the even square numbers.