Subtraction -
5-2=
3
2+2=
4
1x10
1/6
1/6
10,20,30,40,50,60,70,80,90,100
10-6=
4
10+4=
14
2x3
1/4
1/4
By 5s
5,10,15,20,25,30,35,40,45,50
35-12=
23
24+12=
36
6x8
48
1/3
1/3
By 2s
2,4,6,8,10,12,14,16,18,20,22
86-53=
33
215+132=
347
10x11
110
1/8
1/8
By 3s
3,6,9,12,15,18...
354-213=
141
24+16=
40
12x5
60
1/2
1/2
By 4s
4,8,12,16,20,24,28,32..