1. There are 68 coins, different in weight. Find the heaviest and the lightest coins using 100 weighings on a balance scale without weights.
85.1. Let's divide 68 coins into 34 pairs and compare the coins in pairs. Then, among the 34 heavier coins, we will find the heaviest coin in 33 weighings, and among the 34 lighter coins, we will find the lightest coin in 33 weighings.