Negative numbers · Usually met around P5
Negative numbers around us
Which side of 0, then how far from 0.
How to do it
Method
Which side of 0, then how far from 0
5 degrees below zero = −5°C; B2 is like −2
Another way
Number line
−5 is 5 steps left of 0
In full
A number less than 0 is negative, written with a minus sign in front: −5 is said “negative five”. On a thermometer, the marks below 0°C are negative: −5°C is 5 degrees below zero. On a number line, positive numbers are to the right of 0 and negative ones to the left: −5 is 5 steps left of 0. In a lift, the ground floor G is like 0, and B1 and B2, the 1st and 2nd floors below ground, are like −1 and −2. Sea level is 0 m, and 30 m below sea level is written −30 m. To read a negative number, see which side of 0 it is on, then count how far it is from 0; or lay the thermometer on its side and read it as a number line.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
What temperature does the thermometer show?
- A. 14°C
- B. -13°C
- C. -15°C
- D. -14°C
Choose the right answer
Show the answer and working
Answer: D. -14°C
The top of the liquid is 14 marks below 0°C, 1 degree a mark: 14 degrees below zero, which is -14°C.
Example 2
Taking sea level as 0 m, a place at a height of 60 m is below sea level.
True or false?
Show the answer and working
Answer: False
Heights less than 0 (negative) are below sea level, and those more than 0 are above it: see whether 60 has a minus sign.
Example 3
What number is the arrow pointing to on the number line?
- A. -5
- B. 4
- C. -4
- D. -3
Choose the right answer
Show the answer and working
Answer: C. -4
The arrow is 4 steps left of 0, so the number is negative: -4.
Practise it in the game →Negative numbers · Free to start, unlimited questions, no download