Decimal Numbers on a Number Line

Lesson Plan - Get It!

Audio:

A number written with digits after the decimal point (.) is called a decimal number.

A decimal number is not a whole number, which means it is similar to a fraction in that it represents part of a whole.

For example, a decimal number is a number that is between two whole numbers and has a decimal point. Like 0.8 is between the whole numbers 0 and 1. Also, 2.3 is a decimal number between the whole numbers 2 and 3.

A number line can help you understand decimal numbers.

Understanding place value and how to say the decimal number is important to understand how decimals relate to fractions.

Let's take the distance the frog hopped from before. It hopped 1.5 feet. Now, you may be tempted to say "one point five" feet, but that is incorrect.

Let's quickly review a decimal place value chart.

Using the place value chart, 1.5 is said "one and five tenths." Also, 1.05 is said as "one and five hundredths."

• Do you see how these decimals relate to fractions?

A number line helps you visualize numbers by evenly spacing the numbers on a horizontal line. The decimal numbers increase the farther to the right you move. This will be important when it comes to comparing decimals!

On the decimal number line below, there are 10 evenly-spaced sections from 0 to 1. If you start counting at 0, you will count each tenth until you reach "ten tenths," which is equal to one whole.

You can relate money to decimals on a number line by thinking of a dime. A dime is a tenth of a dollar, so ten dimes equal a dollar, or one whole.

Some number lines involve hundredths.

There are 10 evenly spaced sections from 0 to 0.1. If you start counting at 0, you will count each hundredth until you reach "ten hundredths," which is equal to one tenth.

Look at the problem from the beginning of the lesson:

The frog hopped 1.5 feet. Where would the decimal number 1.5 be on a number line?

The decimal number 1.5 has a whole number of 1, which is the number to the left of the decimal. The number 1.5 is halfway between 1 and 2.

In your own words, explain out loud how a number line can help you visualize and plot decimal numbers.

In the Got It? section, you will practice locating decimal numbers on a number line.