8.6. First solution. Divide all the coins into two parts of 20 coins each and weigh them. Since the number of counterfeit coins is odd, one of the piles will weigh more. This means that there is no more than one counterfeit coin in it. Divide it into two piles of 10 coins and weigh them. If the scales are in balance, then all 20 weighed coins are genuine. If one of the pans outweighs, then there are 10 genuine coins on that pan, and among the other 10 coins, there is exactly one counterfeit. Divide these 10 coins into three piles of 4, 4, and 2 coins. In the third weighing, compare the two piles of 4 coins. If they balance, then all 8 coins are genuine and we have found 18 genuine coins. If one of the piles outweighs, then there are 4 genuine coins in it, the other pile contains the counterfeit coin, and the 2 set aside coins are genuine. In total, 16 genuine coins have been found.