Mental Math

1
Mental Math
A Life Long Skill
2
Why Mental Math?

• Calculating in you head is a practical life
  skill.
• Mental math can make written computation easier
  or quicker
• Proficiency in mental math contributes to
  increased skill in estimation
• Mental calculation can lead to a better
  understanding of place value, mathematical
  operations, and basic number sense.
• It is new a challenge each day
• Bi-weekly draws?
• OUR BRAIN IS WITH US WHEREVER WE GO, OUR
  CALCULATOR IS NOT!!

3
Guidelines for Mental Math

• Mental math is DAILY, but not necessarily a test
  daily
• Each test will be 10 questions
• 5 seconds to answer each question
• Test is self corrected, you recorded results
• name goes in for a draw (1, 2, 3 chances)
• If corrected incorrectly no chance to win during
  the next draw.
• If no red pen, no tickets for that day
• Unprepared for three classes eliminates you from
  that weeks draw.
• Strategies used will be discussed

4
Mental Math 1

1. The operation associated with the term addend is
   ?
2. The operation associated with the term quotient
   is ?
3. The operation associated with the term factor is
   ?
4. The operation associated with the term dividend
   is ?
5. The operation associated with the term product is
   ?
6. The operation associated with the term minuend is
   ?
7. The operation associated with the term sum is ?
8. The operation associated with the term subtrahend
   is ?
9. The operation associated with the term is
   divisor?
10. The operation associated with the term is
    difference ?

5
Mental Math 1

1. The operation associated with the term addend is
   
2. The operation associated with the term quotient
   is ?
3. The operation associated with the term factor is
   x
4. The operation associated with the term dividend
   is ?
5. The operation associated with the term product is
   x
6. The operation associated with the term minuend is
   -
7. The operation associated with the term sum is
8. The operation associated with the term subtrahend
   is -
9. The operation associated with the term is divisor
   ?
10. The operation associated with the term is
    difference -

6
Mental Math 2

1. 70 43 113
2. 10 70 3 83
3. 200 - 50 150
4. 50 10 40
5. 500 - 200 300
6. 4 x 4 16
7. 4 x 300 1200
8. 50 ? 10 5
9. 8 ? 4 2
10. 40 ? 1 40

Name the term represented by the number that is
blue.
7
Mental Math 2

1. 70 43 (addend) 113
2. 10 70 3 83 (sum)
3. 200 (minuend) - 50 150
4. 50 10 40 (difference)
5. 500 - 200 (subtrahend) 300
6. 4 (factor) x 4 16
7. 4 x 300 120 (product)
8. 50 ? 10 5 (quotient)
9. 8 ? 4 (divisor) 2
10. 40 (dividend) ? 1 40

8
Mental Math 3

1. 70 x 40 2800
2. 500 43 543
3. 20 ? 5 4
4. 20 x 50 1000
5. 700 300 400
6. 50 50 100
7. 30 ? 2 15
8. 50 - 10 40
9. 8 ? 4 2
10. 100 - 40 60

Name the term represented by the number that is
blue.
9
Mental Math 3

1. 70 x 40 (factor) 2800
2. 500 43 543 (sum)
3. 20 (dividend) ? 5 4
4. 20 (factor) x 50 1000
5. 700 (minuend) 300 400
6. 50 (addend) 50 100
7. 30 ? 2 (divisor) 15
8. 50 - 10 40 (difference)
9. 8 ? 4 2 (quotient)
10. 100 - 40 (subtrahend) 60

10
Mental Math 4

1. When you multiply 2 numbers, the result is called
   the ?
2. The numbers you add together to get a result are
   called the ?
3. How many you take away from the amount you
   started with is called the ?
4. The amount you start with when dividing is called
   the ?
5. The result of dividing 2 numbers is called the ?
6. To find a product, the numbers you multiply are
   called ?
7. The result of 2 numbers added together is called
   the ?
8. The number of equal groups you want to make when
   dividing is called the ?
9. The amount you get when subtracting two numbers
   is called the ?
10. The amount you start with when subtracting is
    called the ?

11
Mental Math 4

1. When you multiply 2 numbers, the result is called
   the product.
2. The numbers you add together to get a result are
   called the addends.
3. How many you take away from the amount you
   started with is called the subtrahend.
4. The amount you start with when dividing is called
   the dividend.
5. The result of dividing 2 numbers is called the
   quotient.
6. To find a product, the numbers you multiply are
   called factors.
7. The result of 2 numbers added together is called
   the sum.
8. The number of equal groups you want to make when
   dividing is called the divisor.
9. The amount you get when subtracting two numbers
   is called the difference.
10. The amount you start with when subtracting is
    called the minuend.

12
Mental Math 5

1. The product of 5 and 2 is ?
2. The sum of 5 and 2 is ?
3. The factors are 3 and 5 the result is ?
4. The difference of 10 and 8 is ?
5. 4 x 100 8 x 1 5 x 1000
6. 50 000 3000 20 7
7. 500 300 40
8. 80 40 20 2
9. 4000 500 3000 20
10. The quotient is 5, the divisor is 6 what is the
    dividend?

13
Mental Math 5

1. The product of 5 and 2 is ? 10
2. The sum of 5 and 2 is ? 7
3. The factors are 3 and 5 the result is? 15
4. The difference of 10 and 8 is ? 2
5. 4 x 100 8 x 1 5 x 1000 5408
6. 50 000 3000 20 7 53 027
7. 500 300 40 840
8. 80 40 20 2 142
9. 4000 500 3000 20 7520
10. The quotient is 5, the divisor is 6 what is the
    dividend? 30

14
Mental Math 6

1. 7000 300 40 3
2. 9000 70 3
3. 2000 50 400 4
4. 50 4000 7 300
5. 5 x 1000 3 x 100 9 x 10 2 x 1
6. 4 x 100 8 x 1 5 x 1000
7. 50 000 3000 20 7
8. 500 300 40
9. 80 40 20 2
10. 4000 500 3000 20

15
Mental Math 6

1. 7000 300 40 3 7343
2. 9000 70 3 9073
3. 2000 50 400 4 2454
4. 50 4000 7 300 4357
5. 5 x 1000 3 x 100 9 x 10 2 x 1 5392
6. 4 x 100 8 x 1 5 x 1000 5408
7. 50 000 3000 20 7 53 027
8. 500 300 40 840
9. 80 40 20 2 142
10. 4000 500 3000 20 7520

16
Mental Math 7

1. 500 3000 70 3
2. 6000 700 3
3. 2000 500 40 4
4. 50 000 30 7 8000
5. 3 x 10 000 1 x 1000 9 x 100 2 x 10 3 x 1
   
6. 4 x 1000 2 x 1 5 x 100
7. 200 300 20 5
8. 500 500 400 24
9. 40 60 20 70 30
10. 4200 500 60

17
Mental Math 7

1. 500 3000 70 3 3573
2. 6000 700 3 6703
3. 2000 500 40 4 2544
4. 50 000 30 7 8000 58 037
5. 3 x 10 000 1 x 1000 9 x 100 2 x 10 3 x 1
   31 923
6. 4 x 1000 2 x 1 5 x 100 4502
7. 200 300 20 5 525
8. 500 500 400 24 1424
9. 40 60 20 70 30 220
10. 4200 500 60 4760

18
Mental Math 8

1. 90 7000 500 6
2. 60 000 400 20 3
3. 300 700 80 4
4. 50 000 30 7 8000
5. 3 x 1000 9 x 100 6 x 10 2 x 1
6. 4 x 1000 2 x 10 000 8 x 100
7. 20 80 30 5 70
8. 900 600 400 72 100
9. 2000 8000 700 30
10. 5100 900 70

19
Mental Math 8

1. 90 7000 500 6 7596
2. 60 000 400 20 3 60 423
3. 300 700 80 4 1084
4. 50 000 30 7 8000 58 037
5. 3 x 1000 9 x 100 6 x 10 2 x 1 3962
6. 4 x 1000 2 x 10 000 8 x 100 24 800
7. 20 80 30 5 70 205
8. 900 600 400 72 100 2072
9. 2000 8000 700 30 10 730
10. 5100 900 70 6070

20
Mental Math 9

1. 20 6000 400 7
2. 50 000 9000 200 30
3. 400 600 3 40
4. 20 000 300 9 4000
5. 5 x 1000 3 x 100 7 x 10 2 x 1
6. 7 x 1000 8 x 10 000 6 x 100
7. 50 90 50 5 10
8. 300 600 700 42
9. 4000 500 500 33
10. 3700 300 76

21
Mental Math 9

• 20 6000 400 7 6427
• 50 000 9000 200 30 59 230
• 400 600 3 40 1043
• 20 000 300 9 4000 24 309
• 5 x 1000 3 x 100 7 x 10 2 x 1 5372
• 7 x 1000 8 x 10 000 6 x 100
• 87 600
• 7) 50 90 50 5 10 205
• 8) 300 600 700 42 1642
• 9) 4000 500 500 33 5033
• 10) 3700 300 76 4076

22
Mental Math 10

• 8 x 8
• 5 x 9
• 4 x 6
• 20 divided by 5
• 3 x 7
• 72 divided by 9
• 7) 7 x 8
• 8) 30 divided by 6
• 9) 7 x 7
• 10) 60 divided by 6

23
Mental Math 10

• 8 x 8 64
• 5 x 9 45
• 4 x 6 24
• 20 divided by 5 4
• 3 x 7 21
• 72 divided by 9 8
• 7) 7 x 8 56
• 8) 30 divided by 6 5
• 9) 7 x 7 49
• 10) 60 divided by 6 10

24
Mental Math 11

• 4 x 8
• 3 x 9
• 7 x 5
• 36 divided by 6
• 9 x 9
• 56 divided by 7
• 7) 2 x 8
• 8) 55 divided by 5
• 9) 7 x 6
• 10) 64 divided by 8

25
Mental Math 11

• 4 x 8 32
• 3 x 9 27
• 7 x 5 35
• 36 divided by 6 6
• 9 x 9 81
• 56 divided by 7 8
• 7) 2 x 8 16
• 8) 55 divided by 5 11
• 9) 7 x 6 42
• 10) 64 divided by 8 8

26
Mental Math 12

• 4 x 3
• 6 x 8
• 8 x 5
• 63 divided by 9
• 4 x 7
• 32 divided by 4
• 7) 2 x 12
• 8) 72 divided by 8
• 9) 7 x 7
• 10) 48 divided by 8

27
Mental Math 12

• 4 x 3 12
• 6 x 8 48
• 8 x 5 40
• 63 divided by 9 7
• 4 x 7 28
• 32 divided by 4 8
• 7) 2 x 12 24
• 8) 72 divided by 8 9
• 9) 7 x 7 49
• 10) 48 divided by 8 6

28
Mental Math 13

• 8 x 3
• 9 x 8
• 9 x 6
• 36 divided by 9
• 4 x 4
• 40 divided by 5
• 7) 3 x 12
• 8) 42 divided by 6
• 9) 7 x 4
• 10) 64 divided by 8

29
Mental Math 13

• 8 x 3 24
• 9 x 8 72
• 9 x 6 54
• 36 divided by 9 4
• 4 x 4 16
• 40 divided by 5 8
• 7) 3 x 12 36
• 8) 42 divided by 6 7
• 9) 7 x 4 28
• 10) 64 divided by 8 8

30
Mental Math 14

1. 200 60 000 4 70
2. 50 80 90 20 10
3. 400 600 3000 400
4. 23 300 7
5. 6 x 1000 2 x 100 0 x 10 2 x 1
6. 9 x 1000 8 x 10 000 6 x 100 4 x 10
7. 9 7
8. 90 70
9. 139 7
10. 390 70

31
Mental Math 14

1. 200 60 000 4 70 60 274
2. 50 80 90 20 10 250
3. 400 600 3000 400 4400
4. 23 300 7 330
5. 6 x 1000 2 x 100 0 x 10 2 x 1 6202
6. 9 x 1000 8 x 10 000 6 x 100 4 x 10 89 640
7. 9 7 16
8. 90 70 160
9. 139 7 146
10. 390 70 460

32
Mental Math 15

1. 500 20 500 80
2. 30 80 70 10 10
3. 200 800 30 400
4. 51 3000 9
5. 8 x 1000 3 x 100 4 x 10 4 x 1
6. 9 x 10 000 8 x 1 6 x 1000
7. 7 5
8. 70 50
9. 127 5
10. 330 37

33
Mental Math 15

1. 500 20 500 80 1100
2. 30 80 70 10 10 200
3. 200 800 30 400 1430
4. 51 3000 9 3060
5. 8 x 1000 3 x 100 4 x 10 4 x 1 8344
6. 9 x 10 000 8 x 1 6 x 1000 96 008
7. 7 5 12
8. 70 50 120
9. 127 5 132
10. 330 37 367

34
Mental Math 16

• 48 21
• 53 34
• 34 52
• 456 120
• 438 340
• 629 310
• 400 231
• 456 42
• 381 405
• 705 220

35
Mental Math 16

• 48 21 69
• 53 34 87
• 34 52 86
• 456 120 576
• 438 340 778
• 629 310 939
• 400 231 631
• 456 42 498
• 381 405 786
• 705 220 925

36
Mental Math 17

• 430 53
• 510 87
• 349 220
• 456 440
• 352 527
• 600 350
• 434 231
• 156 420
• 321 45
• 615 224

37
Mental Math 17

• 430 53 483
• 510 87 597
• 349 220 569
• 456 440 896
• 352 527 879
• 600 350 950
• 434 231 665
• 156 420 576
• 321 45 366
• 615 224 839

38
Mental Math 18

• 974 23
• 320 29
• 341 208
• 677 320
• 425 563
• 60 322
• 400 231
• 424 424
• 333 425
• 610 220

39
Mental Math 18

1. 974 23 997
2. 320 29 349
3. 341 208 549
4. 677 320 997
5. 425 563 988
6. 60 322 382
7. 400 231 631
8. 424 424 848
9. 333 425 758
10. 610 220 830

40
Mental Math 19

• 543 253
• 841 200
• 128 331
• 415 363
• 52 315
• 400 200 387
• 398 502
• 260 540
• 9) 390 208
• 10) 111 111 111

41
Mental Math 19

• 543 253 796
• 841 200 1041
• 128 331 459
• 415 363 778
• 52 315 367
• 400 200 387 987
• 398 502 900
• 260 540 800
• 9) 390 208 598
• 10) 111 111 111 333

42
Mental Math 20

• Five and three tenths
• Thirty two and four hundredths
• Seventy-seven thousandths
• Two hundred four and five hundredths
• Nine hundredths
• 4 0.2
• 30 5 0.9 0.07
• 200 0.8
• 9) (5 x 1) (2 x 0.1) (4 x 0.01)
• 10) 3 x 100 6 x 0.01

43
Mental Math 20

• Five and three tenths 5.3
• Thirty two and four hundredths 32.04
• Seventy-seven thousandths 0.077
• Two hundred four and five hundredths 204.05
• Nine hundredths 0.09
• 4 0.2 4.2
• 30 5 0.9 0.07 35.97
• 200 0.8 200.8
• 9) (5 x 1) (2 x 0.1) (4 x 0.01) 5.24
• 10) 3 x 100 6 x 0.01 300.06

44
Mental Math 21

• Nine and three hundredths
• Thirty two and four tenths
• Seven thousandths
• Three hundred and fifteen thousandths
• Nine hundredths
• 5 0.2 0.06
• 300 50 0.9 0.04
• 20 0.08 3
• 9) (5 x 0.001) (2 x 0.01) (4 x 0.1)
• 10) 3 x 100 6 x 0.1 4 x 1

45
Mental Math 21

• Nine and three hundredths 9.03
• Thirty two and four tenths 32.4
• Seven thousandths 0.007
• Three hundred and fifteen thousandths 300.015
• Nine hundredths 0.09
• 5 0.2 0.06 5.26
• 300 50 0.9 0.04 350.94
• 20 0.08 3 23.08
• 9) (5 x 0.001) (2 x 0.01) (4 x 0.1) 0.425
• 10) 3 x 100 6 x 0.1 4 x 1 304.6

46
Mental Math 22
1)
One Whole
47
2)
48
3)
49
4)
50
5)
51
6)
52
7)
53
8)
54
9)
55
10)
56
Mental Math 22
1)
One and four tenths or 1.4
57
2)
Fifty-three hundredths or 0.53
58
3)
One and three hundredths or 1.03
59
4)
One and Two tenths or 1.2
60
5)
One and thirty-four thousandths or 1. 034
61
6)
Five thousandths or 0.005
62
7)
One and thirteen thousandths or 1.013
63
8)
Two and one hundred forty-two thousandths or 2.142
64
9)
Twenty-two thousandths or 0.022
65
10)
One and five hundredths or 1.05
66
Mental Math 23
One Whole

• 1)
• 2)
• 3)
• 4)
• 5)

67
Mental Math 23
One Whole

• 6)
• 7)
• 8)
• 9)
• 10)

68
Mental Math 23
1.134

• 1)
• 2)
• 3)
• 4)
• 5)

2.016
1.308
2.153
4.231
69
Mental Math 23
1.109

• 6)
• 7)
• 8)
• 9)
• 10)

2.221
1.006
0.342
4.03
70
Mental Math 24
One Whole

• 1)
• 2)
• 3)
• 4)
• 5)

71
Mental Math 24
One Whole

• 6)
• 7)
• 8)
• 9)
• 10)

72
Mental Math 24
One Whole
1.13

• 1)
• 2)
• 3)
• 4)
• 5)

10.37
5.04
21.33
33.61
73
Mental Math 24
One Whole
1.2

• 6)
• 7)
• 8)
• 9)
• 10)

10.5
3.32
1.03
15.3
74
Mental Math 25
One Whole

• 1)
• 2)
• 3)
• 4)
• 5)

75
Mental Math 25
One Whole

• 6)
• 7)
• 8)
• 9)
• 10)

76
Mental Math 25
One Whole
2.05

• 1)
• 2)
• 3)
• 4)
• 5)

0.72
13.06
0.4
30.04
77
Mental Math 25
One Whole
1.27

• 6)
• 7)
• 8)
• 9)
• 10)

0.42
2.5
1.13
13.01
78
Mental Math 26

1. 3.25 or 3.5
2. 2.000 or 2.001
3. 0.98 or 0.89
4. 98.9 or 98.19
5. 10.01 or 10.010
6. 6.6 or 6.60
7. Two hundredths or two thousandths
8. 1.9 or 0.999
9. 1 or 0.95
10. 636 or 663

79
Mental Math 26

1. 3.25 or 3.5
2. 2.000 or 2.001
3. 0.98 or 0.89
4. 98.9 or 98.19
5. 10.01 or 10.010
6. 6.6 or 6.60
7. Two hundredths or two thousandths
8. 1.9 or 0.999
9. 1 or 0.95
10. 636 or 663

80
Mental Math 27

1. 3.25 rounded to the nearest tenth
2. 234.9 rounded to the nearest whole number
3. 1.984 rounded to the nearest hundredth
4. 48.9 rounded to the nearest ten
5. 10.08 rounded to the nearest tenth
6. 6.6 rounded to the nearest whole number
7. 1465.9 rounded to the nearest hundred
8. 7.3 rounded to the nearest whole number
9. 0.6544 rounded to the nearest thousandths
10. 1.95 rounded to the nearest tenth

81
Mental Math 27

1. 3.25 rounded to the nearest tenth 3.3
2. 234.9 rounded to the nearest whole number 235
3. 1.984 rounded to the nearest hundredth 1.98
4. 48.9 rounded to the nearest ten 50
5. 10.08 rounded to the nearest tenth 10.1
6. 6.6 rounded to the nearest whole number 7
7. 1465.9 rounded to the nearest hundred 1500
8. 7.3 rounded to the nearest whole number 7
9. 0.6544 rounded to the nearest thousandths 0.654
10. 1.95 rounded to the nearest tenth 2

82
Mental Math 28

1. 9.252 rounded to the nearest hundredth
2. 2399 rounded to the nearest thousand
3. 5.984 rounded to the nearest tenth
4. 48.55 rounded to the nearest tenth
5. 10.087 rounded to the nearest hundredth
6. 8.8 rounded to the nearest whole number
7. 7535.9 rounded to the nearest hundred
8. 7.22 rounded to the nearest whole number
9. 0.9999 rounded to the nearest thousandths
10. 33.91 rounded to the nearest tenth

83
Mental Math 28

1. 9.252 rounded to the nearest hundredth 9.25
2. 2399 rounded to the nearest thousand 2000
3. 5.984 rounded to the nearest tenth 6
4. 48.55 rounded to the nearest tenth 48.6
5. 10.087 rounded to the nearest hundredth 10.09
6. 8.8 rounded to the nearest whole number 9
7. 7535.9 rounded to the nearest hundred 7500
8. 7.22 rounded to the nearest whole number 7
9. 0.9999 rounded to the nearest thousandths 1
10. 33.91 rounded to the nearest tenth 33.9

84
Mental Math 29

1. 50 x 30
2. 80 x 3
3. 20 x 20
4. 40 x 80
5. 300 x 3
6. 60 x 500
7. 800 x 50
8. 900 x 20
9. 60 x 90
10. 40 x 300

85
Mental Math 29

1. 50 x 30 1500
2. 80 x 3 240
3. 20 x 20 400
4. 40 x 80 3200
5. 300 x 3 900
6. 60 x 500 30 000
7. 800 x 50 40 000
8. 900 x 20 18 000
9. 60 x 90 5400
10. 40 x 300 12 000

86
Mental Math 30

1. 10 x 30
2. 3 x 500
3. 2.4 x 2
4. 5 x 80
5. 100 x 38
6. 6.2 x 2
7. 90 x 50
8. 300 x 20
9. 10 x 96
10. 1.25 x 3

87
Mental Math 30

1. 10 x 30 300
2. 3 x 500 1500
3. 2.4 x 2 4.8
4. 5 x 80 400
5. 100 x 38 3800
6. 6.2 x 2 12.4
7. 90 x 50 4500
8. 300 x 20 6000
9. 10 x 96 960
10. 1.25 x 3 3.75

88
Mental Math 31

1. 100 x 93
2. 30 x 70
3. 0.9 x 2
4. 50 x 60
5. 1 x 3.8
6. 10 x 3.8
7. 200 x 50
8. 30 x 40
9. 10 x 180
10. 1.99 x 2

89
Mental Math 31

1. 100 x 93 9300
2. 30 x 70 2100
3. 0.9 x 2 1.8
4. 50 x 60 3000
5. 1 x 3.8 3.8
6. 10 x 3.8 38
7. 200 x 50 10 000
8. 30 x 40 1200
9. 10 x 180 1800
10. 1.99 x 2 3.98

90
Mental Math 32 denotes an estimate

1. 30 x 90
2. 5 x 9.13
3. 3 x 7.97
4. 7 x 2.06
5. 5.13 x 6
6. 5 x 3.89
7. 10 x 3.8
8. 300 x 50
9. 10 x 340
10. 1.98 x 2

91
Mental Math 32

1. 30 x 90 2700
2. 5 x 9.13 45
3. 3 x 7.97 24
4. 7 x 2.06 14 or 14.42
5. 5.13 x 6 30
6. 5 x 3.89 20
7. 10 x 3.8 38
8. 300 x 50 15 000
9. 10 x 340 3400
10. 1.98 x 2 3.96 or 4.00

92
Mental Math 33 denotes an estimate

1. 20 x 700
2. 9 x 4.21
3. 9 x 0.97
4. 5 x 3.36
5. 5.13 x 6
6. 5 x 3.09
7. 1 x 5.9
8. 10 x 5.9
9. 100 x 66
10. 1.05 x 3

93
Mental Math 33

1. 20 x 700 14 000
2. 9 x 4.21 36
3. 9 x 0.97 9
4. 5 x 3.36 15
5. 5.13 x 6 30
6. 5 x 3.09 15 or 15.45
7. 1 x 5.9 5.9
8. 10 x 5.9 59
9. 100 x 66 6600
10. 1.05 x 3 3.15 or 3.00

94
Mental Math 34

1. 4 x 45
2. 97 x 2
3. 6 x 55
4. 5 x 36
5. 4 x 622
6. 34 x 3
7. 20 x 18
8. 7 x 56
9. 66 x 3
10. 52 x 7

95
Mental Math 34

1. 4 x 45 180
2. 97 x 2 194
3. 6 x 55 330
4. 5 x 36 180
5. 4 x 622 2488
6. 34 x 3 102
7. 20 x 18 360
8. 7 x 56 392
9. 66 x 3 198
10. 52 x 7 364

96
Mental Math 35

1. 45 x 5
2. 76 x 3
3. 61 x 5
4. 54 x 3
5. 4 x 62
6. 43 x 4
7. 3 x 91
8. 4 x 65
9. 9 x 32
10. 5 x 73

97
Mental Math 35

1. 45 x 5 225
2. 76 x 3 228
3. 61 x 5 305
4. 54 x 3 162
5. 4 x 62 248
6. 43 x 4 172
7. 3 x 91 273
8. 4 x 65 260
9. 9 x 32 288
10. 5 x 73 365

98
Mental Math 36

1. 55 x 4
2. 92 x 5
3. 71 x 7
4. 4 x 71
5. 9 x 63
6. 20 x 49
7. 30 x 51
8. 3 x 77
9. 6 x 35
10. 63 x 7

99
Mental Math 36

1. 55 x 4 220
2. 92 x 5 460
3. 71 x 7 497
4. 4 x 71 284
5. 9 x 63 567
6. 20 x 49 980
7. 30 x 51 1530
8. 3 x 77 231
9. 6 x 35 210
10. 63 x 7 441

100
Mental Math 37

1. 10 x 7.5
2. 0.9 x 10
3. 100 x 0.97
4. 10 x 3.36
5. 5.13 x 100
6. 100 x 30.9
7. 10 x 0.018
8. 1000 x 5.9
9. 6.6 ? 10
10. 1.05 x 10

101
Mental Math 37

1. 10 x 7.5 75
2. 0.9 x 10 9
3. 100 x 0.97 97
4. 10 x 3.36 33.6
5. 5.13 x 100 513
6. 100 x 30.9 3090
7. 10 x 0.018 0.18
8. 1000 x 5.9 5900
9. 6.6 ? 10 0.66
10. 1.05 x 10 10.5

102
Mental Math 38

1. 100 x 39.1
2. 9.3 x 10
3. 10 x 0.93
4. 100 x 6.3
5. 3.4 ? 10
6. 5.13 x 10
7. 10 x 30.9
8. 10 x 0.001
9. 1000 x 0.5
10. 10.5 ? 100

103
Mental Math 38

1. 100 x 39.1 3910
2. 9.3 x 10 93
3. 10 x 0.93 9.3
4. 100 x 6.3 630
5. 3.4 ? 10 0.34
6. 5.13 x 10 51.3
7. 10 x 30.9 309
8. 10 x 0.001 0.01
9. 1000 x 0.5 500
10. 10.5 ? 100 0.105

104
Mental Math 39

1. 45.1 ? 10
2. 9.3 ? 10
3. 67 ? 10
4. 6.3 ? 100
5. 3400 ? 100
6. 51.3 ? 10
7. 10 x 39.1
8. 413.1 ? 100
9. 2.5 ? 1000
10. 750.5 ? 100

105
Mental Math 39

1. 45.1 ? 10 4.51
2. 9.3 ? 10 0.93
3. 67 ? 10 6.7
4. 6.3 ? 100 0.063
5. 3400 ? 100 34
6. 51.3 ? 10 5.13
7. 10 x 39.1 391
8. 413.1 ? 100 4.131
9. 2.5 ? 1000 0.0025
10. 750.5 ? 100 7.505

106
Mental Math 40

1. 83 ? 100
2. 4.7 x 10
3. 69.2 ? 10
4. 16.3 ? 100
5. 30.4 ? 10
6. 933 ? 10
7. 10 x 92.1
8. 4 ? 1000
9. 2.5 ? 100
10. 5.2 ? 10

107
Mental Math 40

1. 83 ? 100 0.83
2. 4.7 x 10 47
3. 69.2 ? 10 6.92
4. 16.3 ? 100 0.163
5. 30.4 ? 10 3.04
6. 933 ? 10 93.3
7. 10 x 92.1 921
8. 4 ? 1000 0.004
9. 2.5 ? 100 0.025
10. 5.2 ? 10 0.52