Find PI to the Nth Digit – Enter a number and have the program generate PI up to that many decimal places. No limit to the number of decimals
Fibonacci Value - Enter a number and have the program generate its Fibonacci value. [Fibonacci Sequence Wiki]
Fibonacci Sequence – Enter a number and have the program generate the Fibonacci sequence to that number.
Calculator - A simple calculator to do the 4 basic operations (Later make it scientific).
Prime Factorization – Have the user enter a number and find its prome factors. Extra: Show the exponent of each prime factor as well.
Next Prime Number – Have the program generate prime numbers until the user chooses to stop.
Change Return Program – The user enters a cost of the purchase and then the amount of money given. The program will figure out the change and the number of bills and coins for the change.