Rounding 2-digit to Tens
Adding 2-digit without Regrouping
Rounding 3-digit to Tens
Subtracting 2-digit without Regrouping
Estimating sums/differences
100

34

30

100

24 + 15

39

100

352

350

100

99 - 15

84

100

52 - 31

20

200

85

90

200

16 + 72

88

200

846

850

200

69 - 23

46

200

84 - 56

20

300

62

60

300

40 + 33

73

300

749

750

300

84 - 12

72

300

79 - 66

10

400

37

40

400

19 + 50

69

400

963

960

400

75 - 23

52

400

38 - 14

30

500

12

10

500

82 + 17

99

500

875

880

500

84 - 31

53

500

85 - 42

50

M
e
n
u