Spiro Math

   In Spiro Math, you use addition, subtraction, multiplication and division on four digits to reach a particular target. In the picture above, the digits are 2,8,8,9 and you must manipulate these to get a result of 24. If you get stuck, click on the Hint button to get hints on the solution. When you do get the solution, Spiro Math draws a spirograph as your reward. Spirographs are nifty graphical figures like the one behind the problem pad in the picture above.
   SpiroMath 4 requires Windows XP or Vista and is free software. There is no Mac version available.

                                      
   One day, Pete came trucking in the door from school with news of a game his whole class was playing. The 24 Game consists of a deck of cards, each card with four digits on a side. The idea is to use multiplication, addition, division and subtraction on the four digits to arrive at a result of 24. We played the game together, and I liked it, but every once in a while, I would get stuck. This got frustrating and I thought, “How can I use my computer to solve this problem.”
   With a evening's work, I was able to print out a list of all possible four digit combinations that can be made to yield 24. There are 398 of them, if you don’t count different combinations of the same digits. 9530 if you do. Now I had my list and would never be stuck again. I also had a database of possible problems and started to think of computer games I might make using the idea of the 24 Game. I visited the library the next day and found that there are many games like this. As a class, they are called MADS games (Multiply, Add, Divide, Subtract) and I set about writing my own.
   For months after its completion,  5 5 Pete kept his math skills in good shape by playing Spiro Math for 15 minutes each day