PARTS OF NATURAL NUMBERS  2

PROBLEMS

Do the problem yourself first!

11.  Numbers that end in 0's.  How much is

 a)  A third of 180?  60 b)  A third of 1,800?  600 c)  A fourth of 360?  90 d)  A fourth of 36,000?  9,000 e)  A fifth of 2500?  500 f)  A fifth of 2,500,000?  500,000 g)  A fifth of 200?  40 h)  A fifth of 2,000?  400 i)  An eighth of 400?  50 j)  An eighth of 4,000?  500

12.  How much is

 a)  A third of \$1.20?  \$.40 b)  A fourth of \$2.80?  \$.70 c)  A fifth of \$4.50?  \$.90 d)  A third of \$2.40?  \$.80 e)  An eighth of \$4.00?  \$.50 f)  A sixth of \$3.00?  \$.50 g)  A ninth of \$7.20?  \$.80 h)  A fifth of \$2.00?  \$.40

13.  Increase or decrease by a part.  Last week a blouse cost \$36.
13.  This week the price was reduced by a quarter.  What is the price this
13.  week?   \$27

14.  A photograph measures 9 inches by 12 inches.  If it will be enlarged
13.  by a third, what are the new dimensions?

12 inches by 16 inches.

15.  In 1990, the population was 30,000.  By the year 2000, the population
12   had increased by a fifth.  What was the population in 2000?

36,000

16.  Janet used to earn \$28,000 a year.  In her new job, she makes one
28.  quarter more.  How much does she make in her new job?  \$35,000

17.  A mixed number of times.  If tomatoes costs \$.60 a pound, and
14.  you buy three and a half pounds, how much do you pay?  \$2.10

18.  How much is

18.  a)  Two and a half times 40?  100

18   b)  One and a half times 12?  18

18.  c)  One and a quarter times 20?  25

18.  d)  Two and a quarter times 8?  18

18.  e)  Three and a half times 10?  35

18.  f)  Five and a third times 6?  32

15.  g)  One and a quarter times 100?  125

15.  h)  One and three quarters times 100?  175

19.  Finding a part by decomposing.  Complete the following.

19.   a)  Half of 46 = Half of + Half of = 18.   b)  Half of 58 = Half of 50 + Half of 8 = 25 + 4 = 29

19.   c)  Half of 112 = Half of 100 + Half of 12 = 50 + 6 = 56

19.   d)  A third of 72 = A third of 60 + A third of 12 = 24

19.   e)  A third of 690 = A third of 600 + A third of 90 = 230

19.   f)  An eighth of \$42.40 = An eighth of \$40 +

19.  f)  An eighth of \$42.40 = An eighth of \$2.40 = \$5.30

10.  Can you calculate a third of each one mentally?  How much is two
10.  thirds?

10.   a)  42

42 = 30 + 12.  One third = 10 + 4 = 14.  Two thirds = 28.

10.   b)  195

195 = 180 + 15. One third = 60 + 5 = 65. Two thirds = 130.

11.   c)  234  78; 156  d)  \$22.50  \$7.50; \$15.00

11.   e)  \$14.40  \$4.80; 9.60  f)  \$31.20  \$10.40; \$20.80

11.   Calculate mentally by decomposing.

 a)  A fourth of \$9.20 = \$2.30 b)  A fifth of \$28.50 = \$5.70 c)  A fifth of \$17 = \$3.40 d)  A fourth of \$18 = \$4.50 e)  A fourth of \$112 = \$28 f)  A fifth of \$135 = \$27 g)  A sixth of \$138 = \$23 h)  An eighth of \$51.20 = \$6.40

12.   Write a tenth of each of the following.   Write a hundredth.

 45 27.6 8 0.8 600 \$295 \$50 4.5 2.76 0.8 0.08 60 \$29.50 \$5.00 0.45 0.276 0.08 0.008 6 \$2.95 \$.50

13.  Calculator problems

13.  a)  Two thirds of 82,317 = 54,878

13.  b)  Three fourths of \$318.56 = \$238.92

13.  c)  Four fifths of \$893.50 = \$714.80

13.  d)  Five eighths of \$5,045.33 = \$3,153.33

14.  a)   How many ounces are there in half a pound?
14. a)   (1 pound = 16 ounces)  8 ounces

14.  b)  How many ounces are in a quarter of a pound?  4

14.  c)  How many in three quarters of a pound?  12

14.  d)  How many ounces are in an eighth of a pound?  2

14.  e)  How many in seven eighths of a pound?  14

15.  a)  How many ounces are there in a quarter of a cup?

15.  a)  (1 cup = 8 ounces)  2 ounces

15.  b)  How many ounces are in three quarters of a cup?  6

 c)  How many in a third of a cup? 2 23 c) See Example 9 of Lesson 11:  Inexact division.

16.  a)  How many centimeters (cm) are there in a tenth of a meter?

16.  a)  (1 m = 100 cm)   10

16.  b)  How many centimeters are in a quarter of a meter?  25

16.  c)  How many centimeters are in a fifth of a meter?  20

16.  d)  How many in three fifths of a meter?  60

17.   How many feet are there in three quarters of a mile?

17.  (1 mile = 5,280 feet)   3,960

18  How many yards are there in nine tenths of a mile?

18.  (1 mile = 1,760 yards)  1,584

19.  Percent

19.  a)  What number is a third of 100?
13.  a)  (It is not a whole number. Calculate the answer as a mixed
13.  a)  number with a fraction.)

 33 13
 b)  How much is two thirds of 100? 66 23
 c)  What percent means a third? 33 13 %

19.  d)  How much is a third of \$21?  \$7

 19.     e)  How much is 33 13 % of \$21?  \$7
 19.     f)  How much is 66 23 % of \$21?  \$14

20.  Calculator problem.  Round off to two decimal digits.

20.  a)  A sixth of the class got A.  What percent got A?

100 ÷ 6 16.67%

20.  b)  A seventh of the class got B.  What percent got B?  14.29%

20.  c)  Three eighths of the class got C.  What percent got C?  37.5%

Continue on to the next section.

or