Solve (AB)^2 = ACD, where AB is a two-digit number, ACD is a three-digit number, and A, B, C, D are all different digits.
Both 13 or 14 will work:
13^2 = 169 - All 4 digits different:1, 3, 6, 9
14^2 = 196 - All 4 digits different: 1, 4, 9, 6
