The vertices of a cube are labeled with the numbers 0,1,2,3,4,5,6 and 7, such that no two vertices are labeled with the same number. The sum of any 2 numbers on an edge is prime. What is the maximum sum of the 4 numbers on a face?
18; for the six faces, the sums of opposing sides are 18 and 10, 14 and 14, and 18 and 10. I numbered the vertices as such: plane 7, 6, 1, 4; corresponding plane 0, 5, 2, 3
