What are 40 ways to make change for one dollar?

Answer 1

The answer will depend on which country you refer to because the coinage varies between different countries using dollars as their major currency. However, since you have not bothered to provide that crucial bit of information, I cannot provide a more useful answer.

Answer 2

242 ways, if you use pennies, nickels, dimes, and/or quarters. It is indeed possible to obtain the answer without brute forcing it. You would have to use a bijective function, which maps a countable set to another countable set that is easier to count.

Answer 3

http://www.teachnet.com/lesson/math/293changedollar.html