How_To_Be_Good_At_Math

18 NUMBERS •^ POSITIVE AND NEGATIVE NUMBERS

Positive and

negative numbers

Positive numbers are all the numbers that are greater

than zero. Negative numbers are less than zero, and

they always have a negative sign (−) in front of them.

Negative numbers

have a ‘−’ before them.

Positive numbers

usually have no sign

in front of them.

NEGATIVE NUMBERS

What are positive and negative numbers?

−1−2−3−4−5−6−7−8−9−10 0

If we put numbers on a line called a number

line, like the line on this signpost, we see that

negative numbers count back from zero, while

positive numbers get larger from the zero point.

Negative numbers are numbers

less than zero. In calculations, we

put negative numbers in brackets, like

this (−2), to make them easier to read.

Move left to

count down

from zero

Adding and subtracting positive and negative numbers

Here are some simple rules to remember when we add and subtract

positive and negative numbers. We can show how they work on a simple

version of our numbers signpost, called a number line.

To add a positive number,

Adding a positive number we move to the right

When we add a positive number, we

move to the right on the number line.

2 + 3 = 5

Subtracting a negative number

To subtract a negative number,

we also move right on the number line.

So, subtracting −3 from 2 is the same

as 2 + 3.

2 − (−3) = 5

To subtract a negative number,

we move to the right

−5 −4 −3 −2 −1 0 1 2 3 4 5

−5 −4 −3 −2 −1 0 1 2 3 4 5

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