Multiple choice general knowledge math & puzzles

All prime number's can be written in the form of

  1. 7n+1 or 7n-1

  2. 6n+1 or 6n-1

  3. 5n+1 or 5n-1

  4. 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.