Number Line

A number on the left is less than a number on the right.

Examples:

A number on the right is greater than a number on the left.

Examples:

• 8 is greater than 5
• 1 is greater than −1
• −5 is greater than −8

Try this interactive number line (click to mark):

Example: Lunch

• John borrowed $3 to pay for his lunch
• Virginia borrowed $5 to pay for her lunch
• Alex had enough money for lunch and has $3 left over

Place these people on the number line to find who is poorest and who is richest.

Owing money is negative
Having money is positive

So John has " − 3", Virginia has " − 5" and Alex has "+3"

Now it is easy to see that:

Virginia is poorer than John (−5 is less than −3)
and John is poorer than Alex (−3 is less than 3)
and Alex is, of course, the richest!

Using The Number Line

We can use the number line to help us add. We always move to the right to add.

We can use the number line to help us subtract. We always move to the left to subtract.

Footnote: Absolute Value

Absolute Value means to think only about how far a number is from zero.

For example "6" is 6 away from zero, but "−6" is also 6 away from zero.

So the absolute value of 6 is 6, and the absolute value of −6 is also 6