1.
Count backwards by 3s: 24, 21, 18, ___, 12, 9
2.
Count backwards by 2s: 18, 16, 14, ___, 10, 8
3.
Count backwards by 3s: 18, 15, ___, 9, 6, 3
4.
Count backwards by 2s: 14, 12, ___, 8, 6, 4
5.
Count backwards by 3s: 15, ___, 9, 6, 3, 0
6.
Count backwards by 2s: 10, 8, ___, 4, 2, 0
7.
Count backwards by 3s: 21, 18, 15, ___, 9, 6
8.
Count backwards by 3s: 18, 15, 12, ___, 6, 3
9.
Count backwards by 3s: 15, 12, 9, ___, 3, 0
10.
Count backwards by 2s: 10, 8, ___, 4, 2, 0
11.
Count backwards by 3s: 27, 24, 21, ___, 15, 12
12.
Count backwards by 3s: 21, 18, 15, 12, ___, 6
13.
Count backwards by 3s: 24, 21, ___, 15, 12, 9
14.
Count backwards by 2s: 12, 10, 8, ___, 4, 2
15.
Count backwards by 2s: 14, 12, 10, ___, 6, 4
16.
Count backwards by 3s: 18, 15, 12, ___, 6, 3
17.
Count backwards by 2s: 10, 8, 6, ___, 2, 0
18.
Count backwards by 2s: 12, 10, ___, 6, 4, 2
19.
Count backwards by 3s: 18, 15, 12, ___, 6, 3
20.
Count backwards by 2s: 10, 8, ___, 4, 2, 0