In Might and Magic: Clash of Heroes there is a riddle in the necromancer training room where a skeleton asks you to enter a two-digit number. The number he wants "matches" the number of spider legs, brass coins, and "broken time".
On the walls of the room are three murals, one of a spider with seven legs, one of three hourglasses of which one has fallen and broken, and one of five coins.
I have tried 13, the obvious answer, with no luck. I have also tried 15 assuming the two standing hourglasses still count as "broken time". Neither worked.
(I am playing on the DS but I imagine if the Xbox 360 / Playstation 3 versions follow the same campaign, the riddle has not changed.)