1. Practice Doubles and 1 Group.
2. Practice this way.
2 x 8 = 16
7 x 2 = 14
1 x 8 = 8
5 x 2 = 10
9 x 1 = 9
2 x 3 = 6
9 x 2 = 18
2 x 1 = 2
6 x 2 = 12
1 x 4 = 4
7 x 1 = 7
2 x 7 = 14
1 x 1 = 1
2 x 4 = 8
8 x 2 = 16
3 x 1 = 3
2 x 2 = 4
2 x 6 = 12
1 x 6 = 6
1 x 5 = 5