There are four types of common coins in US currency:
  quarters (25 cents)
  dimes (10 cents)
  nickels (5 cents)
  pennies (1 cent)

There are 6 ways to make change for 15 cents:
  A dime and a nickel;
  A dime and 5 pennies;
  3 nickels;
  2 nickels and 5 pennies;
  A nickel and 10 pennies;
  15 pennies.

How many ways are there to make change for a dollar
using these common coins? (1 dollar = 100 cents).

[Source http://rosettacode.org]
count coins