Mathletics

It's a big plus

100

15+42

57

200

28+64

92

300

63+49

112

400

245+643

888

500

336+585

921

Negative Nancy

100

77-23

54

200

81-35

46

300

92-85

7

400

636-425

211

500

786-687

99

By products

100

4*3

12

200

4*6

24

300

6*7

42

400

12*4

48

500

7*8

56

Divide and conquer

100

12/3

4

200

49/7

7

300

54/6

9

400

56/7

8

500

96/12

8

Roundabout

100

Round to the nearest ten: 9

10

200

Round to the nearest ten: 26

30

300

Round to the nearest ten:199

200

400

Round to the nearest ten: 94

90

500

Round to the nearest hundred: 749

700