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.
Place two coins on each side of the scale. If it indicates that they are "equal", switch them, and place the lighter side into the "24g" pile, and the heavier side into the "25g" pile. Do this three times, for a total of 6 uses of the scale.