Basic Mathematics for College Students

316 Chapter 4 Decimals

PAY TO THE

ORDER OF

David Hoyt612 Lelani

Haiku, HI 67512

82.94

Eighty-two and DOLLARS

, 20

Nordstrom $

Feb. 21 10

45-828-02-33-4660

___^94

100

01537. 6

5060

40

30

20

10

5

70

80

90

100

110

120

20

40

60

80100120

140

160

180

MPH

BAP.O. Box 57Garden Branch

Mango City, HI 32145

MEMO

The decimal 1,537.6 on the odometer

represents the distance, in miles, that

the car has traveled.

The decimal 82.94 repesents the

amount of the check, in dollars.

Shoes

SECTION 4.1

An Introduction to Decimals

The place value system for whole numbers that was introduced in Section 1.1 can be

extended to create the decimal numeration system.Numbers written using decimal

notationare often simply called decimals.They are used in measurement, because it

is easy to put them in order and compare them. And as you probably know, our money

system is based on decimals.

1 Identify the place value of a digit in a decimal number.

Like fraction notation, decimal notation is used to represent part of a whole. However,

when writing a number in decimal notation, we don’t use a fraction bar, nor is a

denominator shown. For example, consider the rectangular region below that has 1 of

10 equal parts colored red. We can use the fraction or the decimal 0.1 to describe the

amount of the figure that is shaded. Both are read as “one-tenth,” and we can write:

The square region on the right has 1 of 100 equal parts colored red. We can use

the fraction or the decimal 0.01 to describe the amount of the figure that is shaded.

Both are read as “one one-hundredth,” and we can write:

Decimals are written by entering the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 into place-

value columns that are separated by a decimal point.The following place-value chart

shows the names of the place-value columns. Those to the left of the decimal point

form the whole-number part of the decimal number, and they have the familiar names

ones, tens, hundreds, and so on. The columns to the right of the decimal point form the

fractional part.Their place value names are similar to those in the whole-number part,

but they end in “ths.” Notice that there is no onethsplace in the chart.

–––^1

100

Fraction:

Decimal: 0.01

1

100

0.01

1

100

––^1

10

Fraction: Decimal:

0.1

1

10

0.1

1

10

Objectives

1 Identify the place value of a

digit in a decimal number.

2 Write decimals in expanded

form.

3 Read decimals and write them

in standard form.

4 Compare decimals using

inequality symbols.

5 Graph decimals on a number

line.

6 Round decimals.

7 Read tables and graphs

involving decimals.