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EXERCISE 12

Find the product of : 1. 2 x 207. 21. 2 x 6087. 41. 2 x 41,203. 2. 3 x 409. 22. 3 x 6074. 42. 3 x 26,207. 3. 4 x 306. 23. 4 X 8096. 43. 4 x 35,705. 4. 5 x 704. 24. 5 x 7048. 44. 5 X 42,609. 5. 6 x 508. 25. 6 x 3409. 45. 6 x 30,926. 6. 7 X 802. 26. 7 x 4706. 46. 7 x 40,289. 7. 8 x 605. 27. 8 X 6808. 47. 8 x 70,443. 8. 9 x 909. 28. 9 x 4307. 48. 9 x 80,625. 9. 2 x 437. 29. 2 x 2763 49. 2 x 77,234. 10. 3 x 526. 30. 3 x 4496. 50. 3 x 82,629. 11. 4 x 823. 31. 4 x 8277. 51. 4 x 47,726. 12. 5 x 715. 32. 5 x 7879. 52. 5 X 83,921. 13. 6 x 412. 33. 6 x 9236. 53. 6 X 72,277. 14. 7 x 813. 34. 7 X 8943. 54.7 x 63,429. 15. 8 x 612. 35. 8 x 9448. 55. 8 X 48,296. 16. 9 x 730. 36. 9 x 7367. 56. 9 x 36,436. 17. 2 x 749. 37. 6 x 9982. 57. 6 X 78,879. 18. 3 x 684. 38. 7 x 7347. 58. 7 X 89,986. 19. 8 x 777. 39. 8 x 8888. 59. 8 x 56,789. 20. 7 X 648. 40. 9 x 9999. 60. 9 x 99,999. 61. What will 48 sheep cost at $7 each ? 62. What will 480 dozen pairs of hose cost at $5 a dozen ?

63. A farmer shipped 9 cases, each containing 360 eggs. How many eggs did he ship?

64. A farmer had 7 acres of onions, and the yield was 562 bushels per acre. How many bushels did he get in all ?

43. Multiplying United States Money. The process here is the same as with other numbers. Simply keep the decimal $23.05 point after the dollars. 7

Thus, to multiply $23.05 by 7, proceed as here shown. $161.35 The explanation is the same as in § 40.

EXERCISE 13 Find the product of:

1. 3 x $1.25. 22. 3 x $15.25. 2. 3 x $2.70. 23. 3 x $21.70. 3. 4 x $2.65. 24. 4 x $12.62. 4. 4 x. $3.25. 25. 4 x $32.15. 5. 5 X $2.63. 26. 5 x $17.20. 6. 5 x $6.31. 27. 5 X $23.11. 7. 6 x $2.48. 28. 6 x $18.90. 8. 6 x $3.72. 29. 6 x $37.50. 9. 7 x $4.28. 30. 7 x $41.16. 10.7 x $5.75. 31. 7 x $37.75. 11. 8 X $3.62. 32. 8 x $21.63. 12. 8 x $6.41. 33. 8 x $82.76. 13. 9 x $3.25. 34. 9 x $35.50. 14. 9 x $7.28. 35. 9 x $47.63. 15. 452 x $7. 36. 2142 x $6. 16. 326 x $6. 37. 3142 x $5. 17. 281 x $5. 38. 4126 x $3. 18. 429 x $8. 39. 2107 x $2. 19. 532 x $3. 40. 4340 x $7. 20. 799 x $9. 41. 2989 x $9. 21. 867 x $4. 42. 5842 x $8.

43. 3 x $121.50. 44. 3 x $271.20. 45. 4 x $125.25. 46. 4 x $306.70. 47. 5 x $321.51. 48. 5 x $248.75. 49. 6 x $328.90. 50. 6 x $542.75. 51. 7 x $128.75. 52.7 x $305.20. 53. 8 x $211.75. 54. 8 x $425.25. 55. 9 x $372.72. 56. 9 x $987.68. 57. 42,341 x $2. 58. 21,421 x $3. 59. 26,401 x $4. 60. 31,620 x $5. 61. 77,217 x $7. 62. 60,509 x $9. 63. 84,748 x $6.

64. At $3 each, what will 37 kegs of nails cost ? 65. At $3.25 each, what will 7 door casings cost ? 66. How much will 2 doors for a house cost at $6.75 each?

67. How much will 7 windows for a house cost at $3.70 each ?

68. At $4.50 per thousand, what will 7 thousand shingles cost?

69. At $17.75 per thousand, what will 8 thousand feet of lumber cost?

70. At $42.75 per thousand, what will 4 thousand feet of pine siding cost?

71. If a man builds 4 cottages costing $1728.75 each, what is the total cost ?

72. At $35.50 per thousand, what will 2 thousand feet of matched pine flooring cost ?

73. At $2.28 per thousand square feet, what will 3 thousand square feet of building paper cost ?

74. At $4.48 each for doors, and $5.62 each for windows, what will 6 doors and 9 windows cost?

75. If a dealer sells 8 building lots at an average price of $287.50 each, how much does he receive for all ?

76. If a real estate dealer pays taxes of $37.75 on each of 9 lots, what is the total tax he pays ?

77. How much will it cost to give some rooms in a house 3 coats of paint, if the cost of each averages $37.50 ?

78. If a builder has 7 men employed at $2.75 a day and 3 at $3.50 a day, how much does he pay them all a day?

79. If a contractor employs 8 men at $3.75 a day, 6 men at $2.90 a day, and 7 men at $2.65 a day, how much does he pay them all a day?

MULTIPLICATION BY POWERS OF TEN

29

44. Powers. The result of taking a number

any

number of times as a factor is called a power of the number.

For example, 3 x 3 = 9, and 9 is called the second power, or square, of 3. So 3 x 3 x 3, or 27, is the third power, or cube, of 3. The successive powers of 10 are 10, 100, 1000, and so on.

45. Multiplying by Powers of 10. To multiply an integer by 10, annex a 0; by 100, two o's; by 1000, three O's.

To multiply United States money by 10, move the decimal point 1 place to the right; by 100, 2 places; by 1000, 3 places. 27 $25.16

360 40

300

400
1080
$7548

144000 That is, to multiply 27 by 40, multiply by 4 and annex a 0.

Also to multiply $25.16 by 300, multiply by 3 and move the decimal point 2 places to the right.

And, in general, consider the case of 400 x 360. Here we see the multiplicand is 36 x 10, that is, 360; the multiplier is 4 x 100, that is, 400; therefore the product is 144 x 1000, that is, 144,000.

Therefore, when the multiplicand and multiplier are integers ending in zeros, or either ends in zeros, multiply without regard to the zeros, but annex to the product as many zeros as there are at the end of the multiplicand and of the multiplier.

EXERCISE 14 Find the product of : 1. 30 x 59.

8. 70 x $430. 2. 40 x 477. 9. 80 x $3.55. 3. 60 X 238. 10. 90 x $4.88. 4. 50 x 470. 11. 70 x $2.66. 5. 60 x 930. 12. 80 x $4.32. 6. 20 x 765. 13. 70 x $7.80. 7. 50 x 642. 14. 90 x $5.60.

15. 300 x 427.
16. 500 x 640.
17. 700 x 4200.
18. 900 x 3500.
19. 800 x $3.75.
20. 500 x $4.80.
21. 900 x 99,000.

46. Multiplying by Larger Multipliers. Required to multiply 4674 by 649.

The multiplier is 600 + 40 + 9. The product is obtained by multiplying by 9, then by 40, and then by 600, and adding the products.

(1) (2) 4674

4674 649

649 9 times the multiplicand 42066 42066 40 times the multiplicand 186960 18696 600 times the multiplicand = 2804400 28044

649 times the multiplicand 3033426 3033426 Zeros at the right of the partial products, since they do not affect the result of the addition, should be omitted as in (2).

Care must be taken, however, to put the right-hand figure of each partial product directly under the figure of the multiplier used to obtain it. Find the product of 2007 times $45.87.

$45.87 The products corresponding to the zeros in the mul

2007 tiplier will be zero, and therefore they need not be written. With this exception the multiplication is per

321.09 formed as in the preceding example. The decimal point

9174 is placed before the cents as in the multiplicand.

$92061.09

EXERCISE 15

Find the product of : 1. 21 x 2648.

9. 67 x 2987. 2. 31 x 4872.

10. 74 x 3692. 3. 42 x 2634.

11. 78 8269. 4. 62 x 3108.

12. 89 x 4871. 5. 44 x 2177.

13. 93 x 3642. 6. 54 x 3623.

14. 96 x 2996. 7. 47 x 3926.

15. 73 x 8989. 8. 56 x 7793.

16. 48 x 7642.

17. 54 x 8387. 18. 73 x 9874. 19. 36 x 7448. 20. 95 x 6877. 21. 68 x 7482. 22. 73 x 8929. 23. 85 x 4832. 24. 63 x 6309.

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