Consider the sets
ABCD={15,22,31,45,56,67,79}={2,3,5,6,7,9,12,24}={14,21,31,40,53,62,78,81,90}={11,12,17,23,54,55,62,98,110,111}.
How many ways are there to choose a number out of each set such that the sum of the four numbers is a multiple of 8?
This problem is posed by Daniel W.