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What Is a Number Line? (Mathematics Lesson)

What Is a Number Line?

A number line is a visual representation of the positive and negative numbers and zero.



Note: The number line goes on left and right forever.

Representing Numbers on a Number Line

A number line allows all numbers to be represented.

Usually only integers are marked on a number line. The marks represent integers, such as -1 and 2 shown below:



Other numbers, that include fractions, can be represented in between the marks, such as -2.5 and 3/2 shown below:



Ordering of Numbers

The further right on the number line a number is, the greater it is. The further left on the number line a number is, the smaller it is:



This means that:

  • any number is greater than any integer to its left.
  • any number is less than any integer to its right.
For example,

  • 3 is greater than 1.
  • -1 is less than 1.

Using the Number Line

A number line can be used to see how to add and subtract numbers.

Read more about how to use a number line to add and subtract.
Interactive Test
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Note

ABSOLUTE NUMBERS AND THE NUMBER LINE

The absolute value, or modulus, of a number is the non-negative value of the number without regard to its sign.

The absolute value of a number is denoted by || either side of the number.

The absolute value of a positive number is just that number:



The absolute value of a negative number is the non-negative value of that number. It is that number with the minus sign ( - ) removed:



On a number line, the absolute value of a number is given by its distance from zero.

It can be seen that both 3 and -3 are 3 away from zero, and so both have an absolute value of 3: