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The problems on this page are sourced from many places but their function is the same: to have fun! We challenge you to get engaged with us as math educators thinking, struggling, and talking about the math involved. Don't sell yourself short and google the answer before you have a chance to grapple with the problems on this page and share your thoughts with your fellow math enthusiast.
The 12 Coins
The 12 Coins
November 2023 Issue of Math Matters
The 12 Coins problem was first heard in conversation many years ago. When doing a bit of light research online, an original source could not be found as it is referenced on many different sites. When the Central team met to discuss ideas this problem came up; without being prompted everyone immediately stopped to think through the possibilities and a really great conversation came out of it.
We challenge you to try and solve The 12 Coins Problem in as FEW moves as possible.
You have 12 coins that all look exactly the same. One is counterfeit and is either heavier or lighter than the other 11. With a balance beam scale, isolate the counterfeit coin in the fewest number of moves.
Variations: use only 9 coins
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