Show:
Add to 20
Subtract within 20
Add to 50
Subtract within 50
Multiplication
100

4+4

8

100

10-2

8

100

25+11

36

100

50-5

45

100

2x2

4

200

2+8

10

200

5-3

2

200

16+23

39

200

22-1

21

200

3x3

9

300

7+6

13

300

17-7

10

300

39+7

46

300

46-4

42

300

4x4

16

400

8+7

15

400

20-7

13

400

22+24

46

400

38-15

23

400

5x5

25

500

12+5

17

500

18-6

12

500

33+17

50

500

42-25

17

500

6x6

36