← Your path
Twelve coins, unknown weight
Your goal
Identify the different coin and determine whether it is heavier or lighter, using at most three weighings.
▤ Your first notebook · Statement, rules and controls
The challenge
Twelve coins look identical. Eleven weigh exactly the same and one has a different weight. You do not know whether it is heavier or lighter. You have a two-pan balance.
- Compare the same number of coins on both pans. Each press of “Weigh” uses one of your three weighings.
- Your conclusion must be the only one consistent with the results. A lucky guess is not enough.
How to play
Select coins and place them on the pans. Press “Weigh” and review the result before arranging the next comparison. Finally, choose the coin and whether it is heavier or lighter.
Hints are optional. Reading an explanation does not complete the level: test your strategy on the board.
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