Card Game 24
learn math the fun way
To play the game, either click the Deal button, or enter any four numbers, preferably positive integers between 1 and 13. Then think of a caculation using addition, subtraction, multiplication and/or division to get the number 24. Click the Show Answer button to show "all" possible calculations.
History Many years ago, three out of four Chinese were farmers and most of them were undereducated. Yet they all have remarkable talent in mental arithmetic; they can tell you the answers for 72/2+83 or 3.8*2.5 almost instantly, sometimes even faster than an abacus (ancient Chinese "calculator"). When I was a kid, I got trained by a Chinese poker card game called twenty-four. Not sure if this game contributed to the Chinese farmers' math talent, but the popularity of it among all young people attests to the truth that most Chinese are good at arithmetic.
The game goes like this. Four people each show one card. You think of a calculation with addition, subtraction, multiplication and division on the numbers shown on the cards to get 24. Card Ace is 1, Jack 11, Queen 12, King 13, excluding big and small Jokers. Whoever comes up with the answer first wins that round. For instance, if the cards are 3, 4, 1, and 9, you can say 3*(4+1)+9 (* here means multiply). Obviously, if you are or your kid is a third- or fourth-grader in school, this game has some educational value.
Upgrade and downgrade If you don't feel challenge playing this game of 24, take a look at my game of 48. (You can change it to any arbitrary number in a matter of minutes if you're comfortable with Javascript.) Or for a younger kid, the game of 12 may be more appropriate.
Update 2012-02 I came across the 24 Game Wikipedia page. It has a nice description of this game, history, theory, and online resources, not including mine though! Since my game was written in early 2004 (archive.org snapshot), to my knowledge, I was the first to bring the game online. And since my program uses Javascript, it can be played offline with no Internet connection other than the initial page save or download. It's interesting to know that the history of the game goes back to the 1960's or earlier in Shanghai. I personally played it in early 1970's in Chongqing.
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