8 byes leaves 60 teams playing => 30 teams winning + the 8 bye teams = 38 teams left. What are you going to do, more byes?

It's really very simple. If the number of teams in your tournament is not a multiple of two, then you subtract the next-highest multiple of two and then double that number. That's how many teams you have playing in the first round, and every one else gets a bye.

68 teams => 68-64 = 4 => 4x2 = 8, so 8 teams play the first round, 60 teams get byes, and there are 64 teams left in the second round

65 teams => 65-64 = 1 => 1x2 = 2, so 2 teams play the first round, 63 teams get byes, and there are 64 teams left in the second round

48 teams => 48-32 = 16 => 16x2 = 32, so 32 teams play the first round, 16 teams get byes, and there are 32 teams left in the second round

96 teams => 96-64 = 32 => 32x2 = 64, so 64 teams play the first round, 32 teams get byes, and there are 64 teams left in the second round