Can you place every number from 1 to 16 on a 4x4 grid such that every pair of neighbouring (horizontally and vertically) numbers sum to a prime? Note that the generated primes can be reused.

A similar question for 3x3 is here: Neighbouring numbers summing to a prime

Good luck!


1 Answer 1


How about

  7 16 13 10
  6  1  4  9
  5  2  3 14
 12 11  8 15

Derived by trial and error (aka insufficient mathematical background)

  • $\begingroup$ Great work! You made this puzzle look easy. Do you want to describe your thinking process? $\endgroup$ Commented Sep 25, 2019 at 4:41
  • 1
    $\begingroup$ Thanks! I just made sure that two odd or two even numbers are never adjacent since that would result to even sums. Filling up the first half of the grid was quite easy. Filling up the second half included swapping numbers whenever necessary. $\endgroup$
    – greysaff
    Commented Sep 25, 2019 at 4:48

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