6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 19 , 20 , 21
8 x 9, 10 x 11, 12 x 13, 14 x 15, 18 x 19
10x11 , 12x14 , 14x17
6x7 , 8x9 , 10x11 , 12x13 , 14x15 , 16x17 , 18x19
8, 12
1/4x5/16 , 3/8x7/16 , 7/16x1/2 , 9/16x5/8 , 11/16x3/4 , 13/16x7/8
