Multiple choice general knowledge math & puzzles All prime number's can be written in the form of 7n+1 or 7n-1 6n+1 or 6n-1 5n+1 or 5n-1 Cant be said. Reveal answer Fill a bubble to check yourself B Correct answer Explanation All primes greater than 3 can be expressed as 6n±1 because numbers of form 6n, 6n±2, 6n±3 are divisible by 2 or 3. For example: 7=6(1)+1, 11=6(2)-1, 13=6(2)+1. The pattern fails for 5n±1 and 7n±1.