Show:
adding one digit
subtracting one digit
adding two digit
subtracting two digit
adding three digit
100

2 + 2

4

100

1 - 1

0
100

10 + 11

21

100

20 - 10

10

100

100 + 100

200

200

3 + 5

8

200

6 - 2

4

200

23 + 11

34

200

30 - 20

10

200

245 + 115

360

300

1 + 7

8

300

8 - 6

2

300

45 + 15

60

300

60 - 15

45

300

987 + 239

1,226

400

9 + 8

17

400

9 - 3

6

400

50 + 25

75

400

34 - 23

11

400

249 + 912

1,161

500

7 + 8

15

500

8 - 3

5

500

87 + 67

154
500

89 - 67

22

500

876 + 876

1,752