18. How much will 7 arithmetics cost at $.82 apiece? 19. At $.35 apiece, how much will 24 chickens cost? 20. A rod is 16.5 feet. How many feet are there in 9 rods?

21. When a man earns $3.65 per day, how much does he earn in 26 days?

22. A pound of cream cheese costs $.115. How much do 126 pounds cost?

23. If an automobile averages 17.75 miles an hour, how far will it travel in 14 hours?

Multiplying a decimal by a decimal.

1. Multiply 1.5 by 4. When a decimal is multiplied by an integer, what do you observe about the number of decimal places in the product?

=

MultiWhen a

2. Multiply .1 by .01; 100-1000 = .001. ply 1.5 by .5; 1.5=18; 18×50=1756.75. decimal is multiplied by a decimal, what do you observe about the number of decimal places in the product?

Written Work

1. Multiply .75 by .3.

Since there are two decimal places in the multiplicand and 1 in the multiplier, point off 3 decimal places in the product, making the answer .225.

Multiply as in integers, pointing off as many decimal places in the product as there are decimal places in both factors.

20. Find the cost of 11.5 yards of cloth at 12 yard.

cents a

21. Mrs. Crane bought 3.5 pounds of steak at $.16 per pound, 6 pounds of sugar at $.05 per pound, 4 pounds of coffee at $.28 per pound, and 3 quarts of cranberries at $.10 per quart. She gave in payment 3 one-dollar bills. How much change should she receive?

22. How much will 41.25 yards of linoleum cost at $1.25 per yard?

23. A train between Los Angeles and San Francisco runs 13.5 hours at the rate of 35.7 miles per hour? What is the distance between the two cities?

24. A mail carrier averages 3.25 miles per hour while delivering mail. If he spends 5.25 hours delivering each day, how far does he walk per day?

25. Find the cost of 5.125 yards of silk at $1.75 a yard. At the same price per yard find the cost of 8.875 yards.

26. At $2.50 per day, how much will 4 men earn in 6.5 days?

27. A cubic foot of water weighs 62.5 pounds. How much do 12.75 cubic feet of water weigh?

Divide and test, placing a decimal point in the quotient, before beginning to divide:

11. Explain why adding naughts to the right of a decimal

does not change its value; thus, .8 .80, .05= .050.

=

It is sometimes necessary to add naughts to the right of the dividend to complete the division.

12. Divide .12 by 5. 5).12=5).120

Observe that in dividing a decimal or a mixed decimal by an integer, the dividend is simply separated or partitioned into equal parts.

Place a decimal point in the quotient directly above or below the decimal point in the dividend before beginning to divide; then divide as in the division of integers.

.75

12 is equal to 12.00, which divided by 16 16)12.00 equals .75.

112

A decimal point must be placed after an 80 integer before naughts are annexed.

2. Compare the quotient of 84 with the quotient of 8040. Compare the quotient of 510 with the quotient of 50 ÷ 100. Compare the quotient of 6 ÷ 3 with the quotient of 600

300.

.8 × 10

.2 x 10

=

8

.08 x 100

8

3. Does multiplying both dividend and divisor by the same number affect the value of the quotient?

4. Multiplying by 10 moves the decimal point how many places to the right? multiplying by 100?

5. In what short way may a decimal be multiplied by 10? by 100? by 1000, etc.?

6. Multiply .5, .25, .025 each by 10; each by 100; each by 1000.