1.
Count backwards by 9s: 72, ___, 54, 45, 36, 27
2.
Count backwards by 3s: 21, 18, 15, ___, 9, 6
3.
Count backwards by 9s: 72, 63, 54, ___, 36, 27
4.
Count backwards by 2s: 12, 10, 8, ___, 4, 2
5.
Count backwards by 4s: 24, 20, 16, 12, ___, 4
6.
Count backwards by 5s: 35, 30, 25, ___, 15, 10
7.
Count backwards by 9s: 63, 54, ___, 36, 27, 18
8.
Count backwards by 9s: 72, 63, 54, 45, ___, 27
9.
Count backwards by 3s: 18, ___, 12, 9, 6, 3
10.
Count backwards by 4s: 36, 32, 28, ___, 20, 16
11.
Count backwards by 4s: 24, 20, 16, 12, ___, 4
12.
Count backwards by 8s: 72, 64, 56, 48, ___, 32
13.
Count backwards by 9s: 45, 36, ___, 18, 9, 0
14.
Count backwards by 2s: 14, 12, ___, 8, 6, 4
15.
Count backwards by 3s: 18, 15, 12, 9, ___, 3
16.
Count backwards by 7s: 63, ___, 49, 42, 35, 28
17.
Count backwards by 3s: 24, 21, 18, 15, ___, 9
18.
Count backwards by 7s: 42, ___, 28, 21, 14, 7
19.
Count backwards by 6s: 36, 30, 24, ___, 12, 6
20.
Count backwards by 6s: 36, 30, 24, 18, ___, 6