weighing puzzle 12 balls of equal size and weight except for 1 in New Logic/Math Puzzles Posted March 5, 2018 · Report reply Put 6 balls on either side. Divide the lighter 6 into two groups of 3 and put them on the scale. take the lighter 3. put one on each side of the scale. if they are balanced, the other one weighs lighter. if they don't, we'll know anyway which one is lighter from the balance.