I learned about this game from a French TV show named "Les Chiffres et Les Lettres". This applet only simulates the first part. The problem of the game is to make a target number out of six given numbers with elementary operations (+, -, *, /). The applet can pose a new problem and can solve it for you or tell you that there is no solution. You can enter your own problem too.
To solve the problem yourself choose any two numbers and an arithmetic operation.
Here is the source of this little Java program. It is free, but you may not use it on commercial web sites. If you use the applet on a page, please link to my homepage.