PARTS OF NATURAL NUMBERS  2

PROBLEMS

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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 .8 600 $295 $50
4.5 2.76 .8 .08 60 $29.50 $5.00
.45 .276 .08 .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 2
3
 
   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 1
3
  b)  How much is two thirds of 100?   66 2
3
c)  What percent means a third?   33 1
3
%

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

19.     e)  How much is 33 1
3
% of $21?  $7
19.     f)  How much is 66 2
3
% 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 ÷ 616.67%

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%


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