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Chapter 4—Decimals
41 Naming Decimals
When you complete the work for this section, you should be able to:  Describe where decimal fractions fall on a number line.
 Identify the three main parts of a decimal fraction.
 Identify decimal place values from tenths to millionths.

Decimal numbers, like fractions, allow us to express fractional parts of a number—including places between the integer values on the number line.In the example shown here, you can see two different points (shown in blue) on a number line that do not fall directly on the integer values. One of the values in this example is between –3 and –2, and the other is somewhere between +2 and +3.
Decimal numbers can be located between the integer values
on a number line.
Definition There are three parts to a decimal number:  An integer
 A decimal point
 A decimal fraction
A decimal consists of an integer and a decimal fraction, separated by a decimal point. 
Example
Here are the three parts of the decimal number, 2.14
Decimal fractions play the same roles in mathematics as the numeratoranddenominator fractions that you have already studied in these lessons. However, you will soon discover that decimal fractions are much more useful and far easier to work with.  This counter runs continuously from decimal value 1.00 to 9.99. 
Naming Decimal Place Values
Just as whole numbers and integers have place values, so do decimal numbers.
Review This figure shows the seven place values for a typical wholenumber value. You've seen this before: ones, tens, hundreds, thousands, tenthousands, and so on. 
All New A Decimal number has three parts, including a wholenumber part. And, just as before, the wholenumber part has place values called tens, hundreds, thousands, and so on. But the decimal fraction part is different. 
In a decimal number, the decimal point is the starting point for determining place values. Place value on the left side of the decimal point are the wholenumber values. Place values on the right side of the decimal point are the decimalfraction place values.
 Place values for the wholenumber part of a decimal number begin with ones and increase in the lefthand direction.
 Place values for the decimal fraction part of a decimal number begin with tenths and increase in the righthand direction.
You can see that the names for the wholenumber and decimalfraction parts of a decimal number are very similar. Whereas wholenumber place values are called tens, hundreds, thousands, and so on, decimalfraction place values are called tenths, hundredths, thousandths, and so on.
Names for the place values found in decimal fractions.
WholeNumber Part  DecimalFraction Part 
tens  tenths 
hundreds  hundredths 
thousands  thousandths 
tenthousands  tenthousandths 
hundredthousands  hundredthousandths 
millions  millionths 
tenmillions  tenmillionths 
hundredmillions  hundredmillionths 
Note There is no equivalent of a 1's place in the fraction part of a decimal number. There is a 1's place in the wholenumber part, but not in the decimal part. 
Examples
 The shaded number in 23.148 is in the hundredths place.
 The shaded number in 1.596 is in the thousandths place.
 The shaded number in 159.19003 is in the hundredthousandth place.
Examples and Exercises
Names of Decimal Places Use these interactive examples and exercises to strengthen your understanding and build your skills.  