Posts filed under ‘The Nine Coins Puzzle’
Suppose you have nine identical coins that all look alike. You also know that all coins are identical in weight except for one, which is lighter than the others, the counterfeit. The difference is only perceptible by using a special balance, but only the coins themselves can be weighed, and it can only be used twice in total.
Can you find the counterfeit coin with only two weighings?