November 13, 2015, when expressed in MM/DD/YY format, is 11/13/15. The MM, DD and YY terms, in that order, form an arithmetic progression. It is non-trivial because the three numbers are different.

The first such date in any given century is 01/02/03. What is the last non-trivial arithmetic progression in the century?

What is the last non-trivial geometric progression in the century?

(In reply to d2 answers by Charlie)

Chapeau !!

Really nice!

Btw,  your solution affected my rating of the puzzle (upgraded it...)

Posted by Ady TZIDON on 2015-11-17 11:16:08