Basic Mathematics for College Students

4.1 An Introduction to Decimals 319

3 Read decimals and write them in standard form.

To understand how to read a decimal, we will examine the expanded form of 4.458 in
more detail. Recall that

To add the fractions, we need to build and so that each has a denominator that
is the LCD, 1,000.

Whole-number part

We have found that

Fractional part
We read 4.458 as “four and four hundred fifty-eight thousandths” because 4.458 is
the same as Notice that the last digit in 4.45 8 is in the thousandths place. This
observation suggests the following method for reading decimals.

(^4) 1,000^458.

4.458  4

458

1,000

 4

458

1,000

 4 

458

1,000

 4 

400

1,000



50

1,000



8

1,000

4.458 4 

4

10



100

100



5

100



10

10



8

1,000

5

100

4

10

4.458 4 

4

10



5

100



8

1,000

Reading a Decimal

To read a decimal:

1. Look to the left of the decimal point and say the name of the whole
   number.


2. The decimal point is read as “and.”


3. Say the fractional part of the decimal as a whole number followed by the
   name of the last place-value column of the digit that is the farthest to the
   right.

We can use the steps for reading a decimal to write it in words.

EXAMPLE (^3) Write each decimal in words and then as a fraction or mixed
number.You do not have to simplify the fraction.
a.Sputnik, the first satellite launched into space, weighed 184.3 pounds.
b.Usain Bolt of Jamaica holds the men’s world record in the 100-meter dash:
9.69 seconds.
c.A one-dollar bill is 0.0043 inch thick.
d.Liquid mercury freezes solid at.
StrategyWe will identify the whole number to the left of the decimal point, the
fractional part to its right, and the name of the place-value column of the digit the
farthest to the right.
WHYWe need to know those three pieces of information to read a decimal or
write it in words.

37.7°F

Self Check 3

Write each decimal in words and

then as a fraction or mixed

number.You do not have to

simplify the fraction.

a.The average normal body

temperature is 98.6ºF.

b.The planet Venus makes one

full orbit around the sun every

224.7007 Earth days.

c.One gram is about

0.035274 ounce.

d.Liquid nitrogen freezes solid

at .345.748°F