Add single digit numbers
6+2=
8
12+15=
27
9-3=
6
20-15=
5
13+4=
17
1+5=
6
13+18=
31
3-1=
2
25-13=
12
30+4=
4+8=
12
17+12=
29
9-4=
5
13-11=
27+7=
34
5+2=
7
12+13=
25
7-3=
4
16-15=
1
38+6=
44
1+9=
10
16+11=
27
8-7=
1
30-20=
10
22+7=
29