Estimation

Addition

100

12 + 14

10 + 10 =

20

200

78 - 49

80 - 50 =

30

300

376 + 302

400 + 300 =

700

400

982 + 876

1,000 + 900 = 

1,900

500

2,045 + 3,899

2,000 + 4,000 =

6,000

Subtraction

100

34 - 11

30 - 10 =

20

200

99 - 12

100 - 10 =

90

300

329 - 29

330 - 30 = 

300

400

853 - 94

900 - 100 =

800

500

1,389 - 412

1,400 - 400 =

1000