Found this. Kinda neat!
On Monday, a backward robber walked into a drugstore, pointed the gun at himself
and handed the storekeeper half of the gold coins in his bag.
The storekeeper, seeing his chance to make a handsome profit, demanded that the
robber should also give him one third of the coins left in the bag.
After counting out this number, the robber had a fit of belligerence and decided
to give one half of the coins instead of one third.
Exactly the same thing happened on Tuesday, Wednesday, Thursday and Friday:
the robber walking into the store with the same three-digit square number
of coins in his bag.
By the end of the week, the storekeeper had gained a cubic number of coins.
How many coins did the storekeeper receive?
No need to show your work; you can if you wish!