7.Sixteen coins, numbered 1 to 16, are each red on one side and blue on the other side. Initially, all coins have their red sides facing up. The coins that are multiples of 2 are turned over. Then the coins that are multiples of 4 are turned over. Then the coins that are multiples of 8 are turned over. Then the coins that are multiples of 16 are turned over. Afterwards, how many of the coins have the red side facing up?
