The 12 balls puzzle, also known as the twelve balls problem or weighing puzzle, is a classic logic puzzle where you must identify one odd ball among twelve using a balance scale in only three weighings.

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  • Desktop: click a ball to select; click-and-drag to box-select.
  • Drag the selected balls onto the left or right scale.
  • Desktop: double-click a ball to mark it excluded (green).
  • Click "Weigh" to compare, then repeat up to three times.
  • Use "Undo" to revert the last weighing or "Clear scale" to reset placements.
  • When ready, enter your guess in the solution form.
Ball pool
Scale
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Weigh history
What is the different ball?
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