Basic Mathematics for College Students

330 Chapter 4 Decimals

WRITING

107. Explain the difference between ten and one-tenth.


108. “The more digits a number contains, the larger it is.”
     Is this statement true? Explain.


109. Explain why is it wrong to read 2.103 as “two and
     one hundred and three thousandths.”


110. SIGNS
     a. A sign in front of a fast food restaurant had the
     cost of a hamburger listed as .99¢. Explain the
     error.
     b. The illustration below shows the unusual notation
     that some service stations use to express the price
     of a gallon of gasoline. Explain the error.


111. Write a definition for each of these words.
     decade decathlon decimal


112. Show that in the decimal numeration system, each
     place-value column for the fractional part of a
     decimal is of the value of the place directly to its
     left.

1

10

REGULAR UNLEADED UNLEADED +

2.79 2.89 2.99

––^9

10

––^9

10

––^9

10

REVIEW

113. a. Find the perimeter of the rectangle shown below.

b. Find the area of the rectangle.

114. a. Find the perimeter of the triangle shown below.

b. Find the area of the triangle.

1 1 –

2

in.

1 1 –

5

in.

––^9

10 in.

3 1 –

2

ft

2 3 –

4

ft

SECTION 4.2

Adding and Subtracting Decimals

To add or subtract objects, they must be similar. The federal income tax form shown

below has a vertical line to make sure that dollars are added to dollars and cents added

to cents. In this section, we show how decimal numbers are added and subtracted using

this type of vertical form.

1 Add decimals.

Adding decimals is similar to adding whole numbers. We use vertical formand stack

the decimals with their corresponding place values and decimal points lined up.

Then we add the digits in each column, working from right to left, making sure that

Income Tax Return for Single and

Joint Filers With No Dependents

Form Department of the Treasury—Internal Revenue Service

Wages, salaries, and tips. This should be shown in box 1 of

your Form(s) W-2. Attach your Form(s) W-2.

Taxable interest. If the total is over $1,500, you cannot use Form 1040EZ.

Unemployment compensation and Alaska Permanent Fund dividends

(see page 11).

Add lines 1, 2, and 3. This is your adjusted gross income.

Attach

Form(s)

W-2 here.

Enclose, but

do not attach,

any payment.

1040EZ

Income

2010

1

2

3

4

1

2

3

4

21,056 89

21,298 95

42 06

200 00

Objectives

1 Add decimals.

2 Subtract decimals.

3 Add and subtract signed

decimals.

4 Estimate sums and differences

of decimals.

5 Solve application problems

by adding and subtracting

decimals.