Addition
21 + 7
28
10 - 8 =
2
Count by 2s from 2 to 10
2,4,6,8,10
24, 26, 28, 30
2s
II ○
21
10 + 10
20
15 - 5 =
10
Count by 2s from 20 to 30
20, 22, 24, 26, 28, 30
55, 65, 75, 85
10s
I ○○○
13
29 + 10
39
27 -8 =
19
Count by 5s from 0 to 20
5, 10, 15, 20
100, 200, 300, 400
100s
○○○ ○○
5
73 + 17
90
30 -15 =
15
Count by 10s from 0 to 100
10, 20, 30, 40, 50, 60, 70, 80, 90, 100
90, 85, 80, 75, 70
5s
II ○○○
23