Weighings. Ask a good question.

Press a coin to move it between the table, the left pan and the right pan, then press Weigh. Both pans must hold the same number of coins: with every coin but one the same weight, the fuller pan would always sink and the reading would say nothing. A coin left on the table is not wasted — what the balance rules out about the pans, it rules out about the table too.

Each coin carries what the balance has settled about it: still either way, could only be heavy, could only be light, or cleared. That bookkeeping is not the puzzle, so the board keeps it for you. The puzzle is the weighing you choose next, made before you know what it will say.

There is no coin hidden behind the board. The balance answers each time in the way that leaves the most answers still possible, so a weighing is never lucky and never unlucky, and a board can always be finished in its par by a good enough plan. When one answer is left standing, name it below the board to finish.

Tab reaches every coin, the pans and the naming controls; Enter or Space presses them. Undo takes back a weighing. Reset starts this board again; Next puzzle begins a new attempt on the next board.

Each board shows its par, the fewest weighings a plan needs. A finished board earns 100 points at par, less 10 for each extra weighing, down to 20. Undo takes back the pans, never a weighing already counted, so the count you see is the count that is scored.

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