We use numbers to show how many or how much there is of something:
- People have 2 eyes
- There are 5 toes on a foot
- There are 7 days in a week
- There are 12 inches in a yard
- You have 15 pennies in your pocket … and so on
We use positive numbers to show these things. Up until now we probably haven’t said “positive numbers” ; we’ve just said “numbers”.
We show positive numbers with a + sign
+5 means positive five
We usually don’t say “positive” even though that is what we mean so…
5 is the same as +5
Using Negative Numbers
- The temperature is 12 degrees colder than yesterday
- I owe my sister 6 dollars
- My friend wants to lose 10 pounds
- The car was driving 5 miles per hour under the speed limit
Negative numbers are less than zero
We need numbers to represent these things too. We use negative numbers.
We show negative numbers with a – sign
-7 means negative seven
Sometimes people say “minus seven” instead of “negative seven” – they both mean the same
Negative numbers let us show values without using lots of words. Negative numbers are useful for calculations.
| Using Words | With Negative Numbers |
| A golfer scored 70 on a par 72 course (two under par) | Her score was -2 |
| A man owed $500 to the bank | His balance was -$500 |
| The quarterback gets sacked and the team loses 15 yards. | The team is -15 yards on the play |
| The temperature changed from 10 degrees above zero during the day to 10 below zero at night | There was a -20 degree change in temperature |
Negative numbers are less than zero
The number line below shows how negative numbers go to the left of zero.
