The Twelve Balls Puzzle

One of these 12 balls is counterfeit — it is either heavier or lighter than the rest.
Find the fake, and tell whether it is heavy or light, using the balance at most 3 times.

The Balls

Click a ball: 1st click puts it on the left pan, 2nd on the right pan, 3rd removes it.

Left panRight pan

The Balance

LEFT PAN
RIGHT PAN

Weighing Log

Your weighings will appear here.

    How to play, and a hint
    1. Click balls to load the pans: first click = left pan, second = right pan, third = back to the shelf.
    2. Press Weigh — the heavier side tips down; if the total weights are equal the scale stays level.
    3. Rearrange the balls freely between weighings. You have exactly 3 weighings.
    4. Press Final answer any time, pick the counterfeit ball and say whether it is heavier or lighter.

    Hint: start by weighing 4 balls against 4 balls — the classic solution always finds the fake in 3 weighings.

    Final Answer

    Which ball is counterfeit?

    And is it…

    Correct!