Counterfeit Coin PuzzleFree, no sign-up

Exactly one coin is fake and its weight differs from the real ones. Put the same number of coins on each pan and press Weigh to see whether the left side is heavier, they balance, or the right side is heavier. Narrow it down to one coin within the allowed weighings, then press Answer and pick it. In the 12-coin puzzle you don't know whether the fake is heavier or lighter, so you must say which as well.

Tap a coin to put it on the left pan, tap again to move it to the right pan, and once more to take it off. When both pans hold the same number of coins, press Weigh. Clear pans takes every coin off. When you know the answer, press Answer and pick the coin (in the 12-coin puzzle, also pick Heavier or Lighter). Every weighing is listed below the coins.

No. If the fake were fixed, anyone could copy someone else's answer. Instead, this scale always gives the result that leaves the most possibilities consistent with everything so far (ties are broken in a fixed order for each day). So guessing never works: you can only pin down the fake in time with weighings that narrow it down whatever the result. The number of weighings is always enough.

By time to the correct answer, shortest first (the clock starts when you first touch a coin). Wrong answers can't be submitted. You only need a nickname, and you can submit up to 30 times a day. The daily puzzle and leaderboard change at midnight Japan time (UTC+9). The server replays your weighings and answer to check them.

Each weighing has three possible results, so three weighings can tell 27 cases apart. With 12 coins that could each be heavier or lighter there are 24 cases, so every weighing must cut the remaining cases to a third or fewer, whatever the result. Start by weighing 4 coins against 4.