History Main / TwelveCoinsPuzzle

* ''VideoGame/VoyageInspiredByJulesVerne'': Appears in this Creator/JulesVerne-inspired adventure game, where you have to isolate the lightest of twelve 'isotopes' in the fewest number of steps, with varying points available depending on which of the above solutions you use.

* ''VideoGame/{{Voyage}}'': Appears in this Creator/JulesVerne-inspired adventure game, where you have to isolate the lightest of twelve 'isotopes' in the fewest number of steps, with varying points available depending on which of the above solutions you use.

* ''TabletopGame/{Pathfinder}}'': In the "Menace under Otari" module, a statue of the god of wealth challenges the players to find a heavy counterfeit coin out of a set of nine, and opens a door to a hidden treasury if they can do it in only two uses of the scales.

** After three weighings [[SchrodingersGun the game determines which coins might be the fake given the information you have, and if there's more than one possibility the game will switch it so that you have the wrong coin]]. Infocom was great.

** In ''Spellbreaker'', it appears using a spell that detects the power level of cubes. Naturally, the spell can be used only three times. And you don't know whether the correct cube will glow ''more'' or ''less'' than the fakes.
** Or only two times, if you [[spoiler:take any of the treasure]], making the puzzle and the game {{Unwinnable}}. [[spoiler:The random number generator will be biased against you if you screw up.]]

[[AC:Web Videos]]

Compare and contrast NeedleInAStackOfNeedles, when something is hidden amongst a slew of its duplicates.

* ''VideoGame/FireEmblemTheSacredStones'': Ewan presents this puzzle to Ross in a support conversation. However, in a slight twist, he doesn't ask how to do it in three weighings: he gives the more generic challenge of asking what is the ''minimum number'' of weighings required (and makes it 25 pebbles, not 12 coins). Ross immediately answers 24 (i.e., [[CuttingTheKnot weighing the pebbles one by one]]), then after some encouragement from Ewan, answers 4. Close, but no cigar - the answer is still 3.

The usual version is 12 coins (or bags, or whatever) with three weighings, which has several solutions, some more intuitive than others. It's easier if you know whether the counterfeits are heavier or lighter than the genuine coins, so in trickier versions of the puzzle, you must figure this out as well. A third variation may give you 13 coins (but you know whether the counterfeits are heavier or lighter) --some of the 12-coins-unknown-weight solutions also work for this (simply leave the extra coin out, and then if it was counterfeit, you'll figure that out in the three weighings). 13-coins-and-unknown-weight is not possible in the standard three weighings.

If you know whether the bad coins are heavier or lighter, the solution is to divide the coins into three groups of four coins each. Weigh group A against Group B. If they are balanced, the bad coin is in group C. If they do not balance, the bad coin is on the side corresponding to the description of the bad coin. (If it is heavier, the heavier side contains the bad coin; if the bad coin is lighter, the lighter side contains it.) Now take the coins in the group known to contain the bad coin and weigh two against two. Again one side will be off in the same direction in which the coin is bad: The counterfeit coin is one of those two. Weigh those two coins against each other.

* ''ARG/PerplexCity'': The ''Poison Pill'' card has a variant, where you must figure out how to identify pills of a different weight from five jars in one weighing.

* ''ARG/PerplexCity'' card has a variant, where you must figure out how to identify pills of a different weight from five jars in one weighing.

* ''VideoGame/{{Drakensang}} 2 The River Of Time'': In order to open a chest, you're given several iron and lead weights and you must put the right number of them in the four boxes around the altar. If you can't find the solution, you can ask the druid Megalesios to solve it for you, but you won't gain any experience.

* ''VideoGame/{{Safecracker}} (1997)'': One puzzle involves a key-weighing machine that can only be used in two moves, in which the objective is to find one out of eight keys that's heavier than the others. Choosing the wrong key or making more than two moves scrambles the keys and resets the puzzle.

* ''VideoGame/{{Safecracker}} (1996)'': One puzzle involves a key-weighing machine that can only be used in two moves, in which the objective is to find one out of eight keys that's heavier than the others. Choosing the wrong key or making more than two moves scrambles the keys and resets the puzzle.