Canada and The United States have a quarter, dime, nickel, and penny (25, 10, 5, and 1 cent coins).

1. The maximum number of coins needed to make change for a dollar (i.e. to make any amount less than 100) is nine coins. For example, nine coins are required to make 99 cents: 3 quarters, 2 dimes, and 4 pennies. What is the only smaller amount that also requires nine coins?

2. Having a 20 cent coin instead of a dime would be more efficient; at most eight coins would be needed to make change for a dollar. See if you can make 89 cents with only eight coins (using 25, 20, 5, and 1 cent coins).

3. There are other coin values that are still more efficient, such as 25, 18, 5, and 1 cent coins. What is the fewest number of these coins needed to make 89 cents?