1. Mental Math
Set 2

2. Mental Math # 1 7.7  100 = 40 x 300 = 500 + 30 + 6000 + 2 = 6 + 8 == =
3 x x x 1 =
46.45 rounded to the nearest tenth =
Five hundred and four thousandths =
Which is larger 98.9 or =

3. Mental Math # 1
7.7  100 = 0.077
40 x 300 =
= 6532
6 + 8 = 14
= 164
= 653
3 x x x 1 = 6032
46.45 rounded to the nearest tenth = 46.5
Five hundred and four thousandths =
Which is larger 98.9 or = 98.9

4. Mental Math # 2 822.4  100 = 50 x 30 = 5 + 800 + 60 + 2000 = 7 + 5 ==
2 x $3.99=
3 x x x 1000 =
rounded to the nearest hundredth =
ten and thirteen thousandths = =

5. Mental Math # 2
822.4  100 = 8.224
50 x 30 = 1500
= 2865
7 + 5 = 12
= 342
2 x $3.99= $7.98
3 x x x 1000 = 2360
rounded to the nearest hundredth = 8.45
ten and thirteen thousandths =
= 1.04 1

6. Mental Math # 3 105 cm = ____ m 2 L = _____ mL 5000 m = _____ km
3.4 mm = _____ cm
90 mL = _____ L
600 g = _____ kg
1 mg = _____ g
3 km = _____ m
0.01 g = _____ mg
20 m = _____ cm

7. Mental Math # 3 105 cm = 1.05 m 2 L = 2000 mL 5000 m = 5 km
3.4 mm = 0.34 cm
90 mL = 0.09 L
600 g = 0.6 kg
1 mg = g
3 km = 3000 m
0.01 g = 10 mg
20 m = 2000 cm

8. Mental Math # 4 6 L = _____ mL 3700 m = _____km and _____m
59 km = _____ m
3.4 cm = _____mm
345 mL = _____L
69 mg = _____ g
1112 g = _____kg
9 km = _____ m
0.08 g = _____ mg
2160 m = _____ km and _____m

9. Mental Math # 4 6 L = 6000 mL 3700 m = 3 km and 700 m 59 km = 59 000 m
3.4 cm = 34 mm
345 mL = L
69 mg = g
1112 g = kg
9 km = 9000 m
0.08 g = 80 mg
2160 m = 2 km and 160 m

10. Mental Math # 5 3900 mm = _____ m 4321 m = _____ km and _____ m
5900 mL = _____ L and _____ mL
47 cm = _____ mm
805 mL = _____ L
6 g = _____ mg
4 kg = _____ g
9 km = _____ hm
8 g = _____ dg
2002 m = _____ km and _____ m

11. Mental Math # 5 3900 mm = 3.9 m 4321 m = 4 km and 321 m
5900 mL = 5 L and 900 mL
47 cm = 470 mm
805 mL = L
6 g = 6000 mg
4 kg = 4000 g
9 km = 90 hm
8 g = 80 dg
2002 m = 2 km and 2 m

12. Mental Math # 6 Have $10, spend $1.25 = Have $10, spend $3.45 =

13. Mental Math # 6 Have$10, spend $1.25 = $8.75

14. Mental Math # 7 Have $10, spend $2.75 = Have $10, spend $3.55 =

15. Mental Math # 7 Have $10, spend $2.75 = $7.25

16. Mental Math # 8 Have $10, spend $2.80 = Have $10, spend $5.35 =

17. Mental Math # 8 Have $10, spend $2.80 = $7.20

18. Mental Math # 9 Have $10, spend $3.35 = Have $10, spend $7.40 =

19. Mental Math # 9 Have $10, spend $3.35 = $6.65

20. Mental Math # 10 Have $10, spend $8.30 = Have $10, spend $1.41 =
$ ? = $10.00
5.2 + ? = 10
Have $20, spend $11.50 =
Have $20, spend $7.68 =
? = 5
? = 5
? = 20

21. Mental Math # 10 Have $10, spend $8.30 = $1.70
$ $6.01 = $10.00
= 10
Have $20, spend $11.50 = $8.50
Have $20, spend $7.68 = $12.32
= 5
= 5
= 20

22. Mental Math # 11 Have $10, spend $5.15 = Have $10, spend $3.57 =
$ ? = $10.00
3.7 + ? = 10
Have $20, spend $12.75 =
Have $20, spend $9.50 =
? = 1
? = 5
? = 20

23. Mental Math # 11 Have $10, spend $5.15 = $4.85
$ $5.39 = $10.00
= 10
Have $20, spend $12.75 = $7.25
Have $20, spend $9.50 = $10.50
= 1
= 5
= 20

24. Mental Math # 12 20 + 14 = 55 + 43 = 38 + 26 = 65 + 27 = 78 + 135 == = = = =

25. Mental Math # 12
= 34
= 98
= 64
= 92
= 213
= 82
= 72
= 93
= 83
= 306

26. Mental Math # 13 46 + 27 = 35 + 48 = 18 + 73 = 94 + 26 = 82 + 225 == = = = =

27. Mental Math # 13
= 73
= 83
= 91
= 120
= 307
= 96
= 98
= 68
= 133
= 290

28. Mental Math # 14 30 + 25 + 70 = 35 + 40 + 60 + 20 = 50 + 95 + 50 == = = = = = =

29. Mental Math # 14
= 125
= 155
= 195
= 210
= 200
= 150
= 230
= 210
= 300
= 1600

30. Mental Math # 15 = = = = = = = = = =

31. Mental Math # 15
= 150
= 210
= 220
= 210
= 280
= 125
= 230
= 1265
= 430
= 1100

32. Mental Math # 16 29 + 75 = 56 + 52= 25 + 54 = 175 + 24 = 90 + 55 == = = = =

33. Mental Math # 16
= 104
= 108
= 79
= 199
= 145
= 125
= 177
= 202
= 308
= 305

34. Mental Math # 17 28 + 75 = 225 + 76 = 25 + 98 = 198 + 28 = 390 + 38 == = = = =

35. Mental Math # 17
= 103
= 301
= 123
= 226
= 428
= 285
= 308
= 202
= 404
= 208

36. Mental Math # 18 2 x 75 x 5 = 2 x 7 x 5 x 5 x 2 = 25 x 9 x 4 =

37. Mental Math # 18
2 x 75 x 5 = 750
2 x 7 x 5 x 5 x 2 = 700
25 x 9 x 4 = 900
10 x 16 x 2 = 320
5 x 20 x 38 = 380
8 x 4 x 5 = 160
97 x 2 x 5 = 970
500 x 33 x 2 =
25 x 2 x 40 = 2000
50 x 56 x 2 = 5600

38. Mental Math # 19 20 x 5 x 8 = 25 x 7 x 4 = 2 x 93 x 5 = 10 x 32 x 2 =

39. Mental Math # 19 20 x 5 x 8 = 800 25 x 7 x 4 = 700 2 x 93 x 5 = 930

40. Mental Math # 20
800  20 =
300  50 =
9000  30 =
630  90 =
4200  60 =
7200  800 =
2700  90 =
200  50 =
770  70 =
3200  800 =

41. Mental Math # 20
800  20 = 40
300  50 = 6
9000  30 = 300
630  90 = 7
4200  60 = 70
7200  800 = 9
2700  90 = 30
2000  50 = 40
770  70 = 11
3200  800 = 4

42. Mental Math # 21
900  30 =
3600  60 =
2400  30 =
6400  80 =
3600  600 =
 700 =
8000  400 =
4500  50 =
1800  30 =
5600  800 =

43. Mental Math # 21
900  30 = 30
3600  60 = 60
2400  30 = 80
6400  80 = 80
3600  600 = 6
 700 = 50
8000  400 = 20
4500  50 = 90
1800  30 = 60
5600  800 = 7

44. Mental Math # 22
480  6 =
3500  70 =
3000  50 =
 60 =
600  60 =
 400 =
8100  900 =
6300  90 =
1200  40 =
3200  800 =

45. Mental Math # 22
480  6 = 80
3500  70 = 50
3000  50 = 60
 60 = 300
600  60 = 10
 400 = 40
8100  900 = 9
6300  90 = 70
1200  40 = 30
3200  800 = 4

46. Mental Math # 23 228  2 = 255  5 = 339  3 = 168  4 = 300  50 =
726  6 =
990  90 =
200  5 =
714  7 =
342  3 =

47. Mental Math # 23
228  2 = 114
255  5 = 51
339  3 = 113
168  4 = 42
300  50 = 6
726  6 = 121
990  90 = 11
200  5 = 40
714  7 = 102
342  3 = 114

48. Mental Math # 24 530  5 = 369  3 = 322  2 = 464  4 = 600  30 =
816  8 =
8000  40 =
260  5 =
147  7 =
189  9 =

49. Mental Math # 24
530  5 = 106
369  3 = 123
322  2 = 161
464  4 = 116
600  30 = 20
816  8 = 102
8000  40 = 200
260  5 = 52
147  7 = 21
189  9 = 21

50. Mental Math # 25 125 + 35 = 2000 + 50 + 400 + 4 = 4.2 + 3 + 0.8 = 23 =
$ $3.85 =
65 + ? = 100
90 x 50 =
135  5 =
100 x =
60 =

51. Mental Math # 25
= 160
= 2454
= 8
23 = 8
$ $3.85 = $6.15
= 100
90 x 50 = 4500
135  5 = 27
100 x 0.15 = 15
60 = 1

52. Mental Math # 26 375 + 45 = 200 + 60 + 140 = 31 = 2.7 + 3 + 1.3 =
You give $5 for a purchase costing $ What is your change?
? = 1000
2800 in scientific notation is =
284  2 =
2.9 x 100 =
38.9  10 =

53. Mental Math # 26
= 420
= 400
31 = 3
= 7
You give $5 for a purchase costing $ What is your change? $2.45
= 1000
2800 in scientific notation is = 2.8 x 103
284  2 = 142
2.9 x 100 = 290
38.9  10 = 3.89

54. Mental Math # 27 = = =
234.5 in scientific notation =
You give $5 for a purchase costing $ What is your change?
? = 1000
40 x 500 =
396  3 =
5.3 m equals ___ cm =
82.9  10 =

55. Mental Math # 27
= 558
= 2830
= 8
234.5 in scientific notation = x 102
You give $5 for a purchase costing $ What is your change? $1.70
= 1000
40 x 500 =
396  3 = 132
5.3 m equals 530 cm
82.9  10 = 8.29

56. Mental Math # 28 = =
32 = =
$ $6.75 =
? = 100
3000 x 20 =
350  5 =
237  100 =

57. Mental Math # 28
= 6273
= 3850
32 = 9
= 49.8
$ $6.75 = $3.25
= 100
3000 x 20 =
350  5 = 70
237  100 = 2.37
2.304

58. Mental Math # 29 285 + 65 = 4000 + 7 + 500 + 30 = 6.3 + 0.4 + 1.7 == = =
33 =
$ $11.95 =
? + 55 = 200
3 x 700 =
1000  50 =
100 x 0.65 =
636  3

59. Mental Math # 29
= 350
= 4537
= 8.4
33 = 27
$ $11.95 = $8.05
= 200
3 x 700 = 2100
1000  50 = 20
100 x 0.65 = 65
636  3 = 212

60. Mental Math # 30 =
30 = = =
$ $59.00 =
? + 85 = 200
200 x 40 =
1000  20 =
100 x 4.5 =
842  2

61. Mental Math # 30
= 455
30 = 1
= 9.3
= 460
$ $59.00 = $41.00
= 200
200 x 40 = 8000
1000  20 = 50
100 x 4.5 = 450
842  2 = 421

62. Mental Math # 31 =
24 = =
350 =
$ $3.80 =
65 + ? = 300
90 x 30 =
15cm equals __dm =
1000 x 0.15 =
560  5 =

63. Mental Math # 31
= 235
24 = 16
= 8.8
350 = 1
$ $3.80 = $6.20
= 300
90 x 30 = 2700
15cm equals 1.5 dm
1000 x 0.15 = 150
560  5 = 112

64. Mental Math # 32 250 + 125 = 8m equals ___dm 2.3 + 5.8 + 1.7 = 51 =
$ $6.99 =
95 + ? = 300
500 x 70 =
550  5 =
10 x =
361.1  100 =

65. Mental Math # 32 250 + 125 = 375 8m equals 80 dm =
= 9.8
51 = 5
$ $6.99 = $13.01
= 300
500 x 70 =
550  5 = 110
10 x = 13.3
361.1  100 = 3.611

66. Mental Math # 33 8 410 000 in scientific notation = 80 =
$ $ = =
$ $2.10 =
? = 1000
600 x 3 =
446  4 =
2.11 x 1000 =
762.2  100 =

67. Mental Math # 33 8 410 000 in scientific notation = 8.41 x 106 80 = 1
$ $ = $17.80
= 15.3
$ $2.10 = $7.90
= 1000
600 x 3 = 1800
446  4 = 111 R2
2.11 x 1000 = 2110
762.2  100 = 7.622

68. Mental Math # 34 355.5 in scientific notation = 90 km equals ____ m=
1000 – 230 =
$ $9.90 =
180 + ? = 500
500 x 20 =
559  5 =
10 x 27.3 =
590.1  100 =

69. Mental Math # 34 355.5 in scientific notation = 3.555 x 102
90km equals m
= 9.6
1000 – 230 = 770
$ $9.90 = $10.10
= 500
500 x 20 =
559  5 = 111 R4
10 x 27.3 = 273
590.1  100 = 5.901

70. Mental Math # 35 If = 1, then = 530 000 in scientific notation =
7.95m equals ____cm =
1000 – 440 =
You give $10.00 for a purchase costing $ What is your change?
? = 1000
672  6 =
769.1  10 =
3.4 x 102 =

71. Mental Math # 35
If = 1, then = 12.3
in scientific notation = 5.3 x 105
7.95m equals 795cm
= 8.5
1000 – 440 = 560
You give $10.00 for a purchase costing $ What is your change? $3.08
= 1000
672  6 = 112
769.1  10 = 76.91
3.4 x 102 = 340

72. Mental Math # 36 If = 1, then = 385 000 = 5.1 + 5.1 + 7.3 ==
$ $6.75 =
? = 100
3000 x 20 =
350  5 =
4.2 x 1000 =
237  10 =

73. Mental Math # 36 If =1, then = 2.3 385 000 = 3.85 x 105
= 17.5
= 49.8
$ $6.75 = $3.25
= 100
3000 x 20 =
350  5 = 70
4.2 x 1000 = 4200
237  10 = 23.7

74. Mental Math # 37 Two squared added to three squared =
2L equals ___ mL = = =
You give $5 for a purchase costing $ What is your change?
? = 1000
200 x 80 =
384  2 =
2.9 x 100 =
37  10 =

75. Mental Math # 37 Two squared added to three squared = 13
2L equals 2000 mL =
The difference of 52 and 22 =
= 3840
You give $5 for a purchase costing $ What is your change? $2.45
= 1000
200 x 80 =
384  2 = 192
2.9 x 100 = 290
37  10 = 3.7

76. Mental Math # 38 53 dam = ____ m 2 x 103 =
The difference of 52 and 22 = =
You give $5 for a purchase costing $ What is your change?
? = 1000
40 x 500 =
396  3 =
5.3 x 100 =
82  10 =

77. Mental Math # 38
53 dam = 530 m
2 x 103 = 2000
The difference of 52 and 22 = 21
= 8.9
You give $5 for a purchase costing $ What is your change? $1.70
= 1000
40 x 500 =
396  3 = 132
5.3 x 100 = 530
82  10 = 8.2

78. Mental Math # 39 = = = =
You give $10 for a purchase costing $ What is your change?
? = 1000
50 x 60 =
784  7 =
47.3 x 10 =
2444  100

79. Mental Math # 39
= 373
= 6660
= 16.5
= 7.9
You give $10 for a purchase costing $ What is your change? $4.01
= 1000
50 x 60 = 3000
784  7 = 112
47.3 x 10 = 473
2444  100 = 24.44

80. Mental Math # 40 = = =
8.9 – 4.8 =
You give $20 for a purchase costing $1.90 What is your change?
? = 1000
90 x 20 =
575  5 =
0.633 x 100 =
71.4  10

81. Mental Math # 40
= 3743
= 7450
= 19
8.9 – 4.8 = 4.1
You give $20 for a purchase costing $1.90 What is your change? $18.10
= 1000
90 x 20 = 1800
575  5 = 115
0.633 x 100 = 63.3
71.4  10 = 7.14