CHAPTER 1 | WHOLE NUMBERS AND DECIMAL NUMBERS
EXERCISE 1.5
Answers to the odd numbered problems are available online
Read the decimal numbers in Problems 1 and 2 aloud to your group (in as many ways as you can,
referring to the examples above). Everyone must take a turn to read the numbers and other members
of the group may correct you.
1.
2.
(a) 357.23
(b) 1,850.67
(c) 1,368,354.55
(d) 3,505.50
(e) 1.9950
(f) $840,577.45
(g) $12,345,125.75
(h) $1,245.55
(i) $25,650.85
(a) 125.55
(b) 4,350.87
(c) 2,250,765.98
(d) 9,999.87
(e) 1.1035
(f) $100,840.50
(g) $11,350,986.10
(h) $5,540.75
(i) $30,780.75
Read the decimal numbers in Problems 3 and 4 to your class to make sure that everyone is reading the
numbers correctly.
3.
4.
(a) 12.55
(b) 845.12
(c) 12,234,111.75
(d) 1,756.85
(e) 0.1287
(f) $120,747.12
(g) $19,900,118.50
(h) $2,222.75
(i) $16,234.12
(a) 196.75
(b) 9,458.76
(c) 995.83
(d) 89,750,744.45
(e) 0.1555
(f) $12.75
(g) $50.987.89
(h) $119,093,489.75
(i) $12,569.55
Read the decimal numbers in Problems 5 and 6 to your group and then to your class as many ways as you can.
5.
6.
1.6
(a) 123.90
(b) 19,944.89
(c) 1,283,994.50
(d) 1.7783
(e) 0.9982
(f) $0.75
(g) $12,895.75
(h) $1,450,875.90
(i) $12,650,755.75
(a) 1.10
(b) 25.55
(c) 1,235,983.80
(d) 1.9983
(e) 0.0024
(f) $0.50
(g) $18,933.65
(h) $130,250.75
(i) $1,111,234.45
ROUNDING DECIMAL NUMBERS
As we have learned in rounding whole numbers, sometimes it is easier and just as meaningful to
communicate an approximate value of a number rather than its exact value. At these times, the number
is rounded to its approximate value.
EXAMPLE
An accountant at a company may calculate your hourly pay to be $15.7513. However,
you will be paid the amount rounded to the nearest cent which is $15.75. The reason is
that you cannot receive a part of a cent as a payment.
In this section, you will learn how to round decimal numbers.
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1.6 ROUNDING DECIMAL NUMBERS
STEPS TO ROUND DECIMAL NUMBERS
• Identify the digit to be rounded by underlining it.
• If the digit to the right of the underlined digit is:
• 5 or more than 5, then add 1 to the underlined digit.
• Less than 5, then do not add 1 to the underlined digit.
• Remove all the digits to the right of the underlined digit.
EXAMPLES OF ROUNDING DECIMAL NUMBERS TO THE NEAREST TENTH, HUNDREDTH, THOUSANDTH, ETC.
(a) Rounding 3.24 to the nearest tenth is the same as rounding it to the nearest 1 decimal place,
which results in 3.2.
(b) Rounding 2.26 to the nearest tenth is the same as rounding it to the nearest 1 decimal place,
which results in 2.3.
(c) Rounding 4.184 to the nearest hundredth is the same as rounding it to the nearest 2 decimal
places, which results in 4.18.
(d) Rounding 1.927 to the nearest hundredth is the same as rounding it to the nearest 2 decimal
places, which results in 1.93.
EXAMPLES OF ROUNDING DOLLAR AMOUNTS TO THE NEAREST CENT (SAME AS ROUNDING TO THE
NEAREST 2 DECIMAL PLACES)
(a)
(b)
(c)
(d)
Rounding $10.1123 to the nearest cent is $10.11.
Rounding $22.5581 to the nearest cent is $22.56.
Rounding $189.9952 to the nearest cent is $190.00.
Rounding $0.999101 to the nearest cent is $1.00.
EXAMPLES OF ROUNDING DECIMAL NUMBERS TO WHOLE NUMBERS (SAME AS ROUNDING TO THE
NEAREST ONES)
(a) Rounding 4.36 to the nearest whole number is 4.
(b) Rounding 899.91 to the nearest whole number is 900.
(c) Rounding $15.54 to the nearest dollar is $16.
EXERCISE 1.6
Answers to the odd numbered problems are available online
Round the decimal numbers in Problems 1 to 6 to the place values specified in the brackets.
1.
(a) 1.83942 (nearest tenth)
(b) 11.15784 (nearest tenth)
(c) 21.85131 (nearest hundredth)
(d) 190.9954 (nearest hundredth)
(e) 5.598332 (nearest thousandth)
(f) 91.22498 (nearest thousandth)
(g) 0.9841 (nearest 1 decimal place)
(h) 1.5023 (nearest 2 decimal places)
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CHAPTER 1 | WHOLE NUMBERS AND DECIMAL NUMBERS
2.
3.
4.
5.
6.
(a) 5.95934 (nearest tenth)
(b) 10.31596 (nearest tenth)
(c) 1.67285 (nearest hundredth)
(d) 384.9671 (nearest hundredth)
(e) 2.999501 (nearest thousandth)
(f) 70.99846 (nearest thousandth)
(g) 0.6512 (nearest 1 decimal place)
(h) 9.99610 (nearest 2 decimal places)
(a) $1.94482 (nearest cent)
(b) $22.15843 (nearest cent)
(c) $181.12541 (nearest cent)
(d) $2,200.128 (nearest cent)
(e) $10.9381 (nearest cent)
(f) $0.18224 (nearest cent)
(a) $9.19514 (nearest cent)
(b) $67.18114 (nearest cent)
(c) $902.01901 (nearest cent)
(d) $1,929.675 (nearest cent)
(e) $81.9871 (nearest cent)
(f) $0.00912 (nearest cent)
(a) 18.1832 (nearest whole number)
(b) 185.891 (nearest whole number)
(c) 2,000.12 (nearest whole number)
(d) $1.01 (nearest dollar)
(e) $18.46 (nearest dollar)
(f) $0.9102 (nearest dollar)
(a) 120.220 (nearest whole number)
(b) 99.59 (nearest whole number)
(c) 1,545.18 (nearest whole number)
(d) $2.56 (nearest dollar)
(e) $54.19 (nearest dollar)
(f) $0.9893 (nearest dollar)
7.
Henry’s job paid him $895.75 every week. Express his weekly pay rounded to the nearest dollar.
8.
According to Amanda’s calculations, her business partner owed her $780.7812. Express the
amount owed rounded to the nearest cent.
9.
The meter in the gas station displayed that 55.558 litres of gas were filled into the tank of a car.
Express this amount rounded to the nearest two decimal places.
10. Mary’s garden had an accurate measurement of 11.358 metres in length and 5.459 metres in
width. Express these measurements rounded to the nearest whole number.
1.7
ADDING AND SUBTRACTING
DECIMAL NUMBERS
ADDING DECIMAL NUMBERS
When adding decimal numbers, place the numbers in columns, and make sure that the decimal point
of each number is aligned. Then, perform the addition operation.
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