5^31-5^29
=5^29(5^2-1)
=5^29(25-1)
=5^29(24) ...a
100=5^2x4 ...b
Divide a by b
5^29(24) / 5^2 x 4
=5^27 x 6
This, 5^31-5^29 is divisible by 100.
