Page 299 - Basic College Mathematics with Early Integers

4.1 INTRODUCTION TO DECIMALS
Objectives

Know the Meaning of Place Value
for a Decimal Number and Write
Decimals in Words. Objective Decimal Notation and Writing Decimals in Words
Like fractional notation, decimal notation is used to denote a part of a whole.
Write Decimals in Standard Form.
Numbers written in decimal notation are called decimal numbers, or simply
Write Decimals as Fractions. decimals.The decimal 17.758 has three parts.
1 7 . 7 5 8
Compare Decimals.
Whole æ Decimal
number part
Round Decimals to Given Place s
part s
Values. s
s
Decimal point
In Section 1.2, we introduced place value for whole numbers. Place names and
place values for the whole number part of a decimal number are exactly the same.
Place names and place values for the decimal part are shown below.

Hundred-thousands Ten-thousandths Hundred-thousandths

Notice that place Ten-thousands Thousands Hundreds Hundredths Thousandths Millionths
values to the left of the Millions Tens Ones Tenths
decimal point end in “s.” Place 1,000,000 100,000 10,000 1000 100 10 1 1 1 1 1 1 1
values to the right of the deci- 10 100 1000 10,000 100,000 1,000,000
mal point end in “ths.” 1 7 . 7 5 8

1
Notice that the value of each place is of the value of the place to its left. For
10
example,

1 1 1 1 1
1 # = and # =
10 10 10 10 100
c c c c
ones tenths tenths hundredths
The decimal number 17.758 means

1 ten 7 ones 7 tenths 5 hundredths 8 thousandths
T T T T T T T T T
2 2 2 2 2
1 1 1
#
#
or 1 10 + 7 1 + 7 # + 5 # + 8 #
10 100 1000
7 5 8
or 10 + 7 + + +
10 100 1000
Copyright 2012 Pearson Education, Inc.
Writing (or Reading) a Decimal in Words

Step 1: Write the whole number part in words.
Step 2: Write “and” for the decimal point.

Step 3: Write the decimal part in words as though it were a whole number,
followed by the place value of the last digit.
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