You have 12 coins, six weigh 24 grams and six weigh 25 grams. You also have the broken scale from Five Weights and a Broken Scale
Sort the 12 coins into the group of 24g coins and the group of 25g coins using that broken scale no more than 9 times.
(In reply to Solution, I think.
by Cougar Draven)
And if the second weighting also indicates "equal"?
I'm afraid this doesn't work -- for example, if you took two 24g coins,
you'd place one in the 24g pile (OK) and the other in the 25g pile