1

2

10 + 30 = 40

1 + 3 = 40

3

15 + 30 = 45

1 + 3 = 45

4

45 + 30 = 15

4 + 3 = 15

5

30 + 10 = 20

3 + 1 = 20

6

100 + 7 = 107

107

7

100 + 30 = 130

130

8

156 + 3 = 159

150 +(6+ 3) = 159

9

156 + 20 = 176

156 +(5+ 2) = 176

100 + (50 +20) = 176

10

156 - 3 = 153

150 +(6+ 3) = 153

11

156 - 20 = 136

156 +(5 - 2) = 136

100 + (50 -20) = 136

12

2 + 2+ 2 +2= 8

3 + 3+ 3 = 9

13

100 - 3 = 97

100 - 5 = 95

14

256 + 2 = 258

200 + (6 +2) = 258

15

256 + 20= 276

200 + (50 +20) = 276

16

2 x 3 = 6

4 x 5 = 20

17

10 + 30 + 7 = 47

1 + 3 = 4

18

10 + 30 + 57 = 97

1 + 3 + 5= 9