The best denominations for coins

and how many to keep in your wallet

What is the best way to give change so as to minimize the number of coins used? The obvious way to do this using the widely used coins in the US (25, 10, 5, and 1 cent) is to use the greedy algorithm. This works as follows: start with the largest value coin, keep giving that coin until the amount left is less than the value of the coin, then move to the…