You have 10 stacks of coins, each consisting of 10 quarters. One entire stack is counterfeit, but you do not know which one. You do know the weight of a genuine quarter and you are also told that each counterfeit quarter weights one gram more than it should. You may weight the coins on a pointer scale that indicates to you the weight in grams of the substance being weighted. Show how the counterfeit stack can be identified by a single weighting.