Question

Given the check digit is 3, find the missing X for the master card number 5164 2X13 2705 0183

Answer 1

9

Explanation:

So there's 3 1's, 2 2's, 2 3's, 1 4, 2 5's, a 6, a 7, an 8, 2 0's, and no 9's.