• # Revision:Directed Numbers

TSR Wiki > Study Help > Subjects and Revision > Revision Notes > Mathematics > Directed Numbers

Numbers can either be positive or negative. The name directed number comes from thinking of a number line. The directed part saying which direction from 0 on the number line the number lies: positive numbers being one direction and negative being the other.

Sometimes brackets are put around negative numbers to make them easier to read, e.g. (-2). Other times a '+' or '-' sign is written in front of the number. Both methods are used and you need to be happy using both. If a number is positive, the + is usually missed out before the number. So 3 is really (+3) or +3.

Adding and multiplying combinations of positive and negative numbers can cause confusion and so care must be taken.

• Two 'pluses' make a plus - so if two '+' signs are written next to each other you can replace them with a single '+' sign.
• Thus -3 + (+2) = -3 + 2 = -1
• Two 'minuses' make a plus - so if two '-' signs are written next to each other, you can replace them with a single '+' sign.
• Thus 6 - (-2) = 6 + 2 = 8
• A plus and a minus make a minus - so if one of each sign sit next to each other, then you can replace them with just a '-' sign.
• Thus -4 - (+3) = -4 - 3 = -7 and 3 + (-7) = 3 - 7 = -4

Basically when adding and subtracting directed numbers different signs next to each other mean subtract, the same signs next to each other means add.

## Multiplication and Division

Here there are again three simple rules to follow:

• If two positive numbers are multiplied together or divided, the answer is positive.
• Thus 2 x 4 = 8 and 10 ÷ 2 = 5
• If two negative numbers are multiplied together or divided, the answer is positive.
• Thus (-2) x (-4) = 8 and (-10) ÷ (-2) = 5
• If a positive and a negative number are multiplied or divided, the answer is negative.
• Thus (-2) x 4 = (-8) and 10 ÷ (-2) = (-5)

So basically, when multiplying or dividing two numbers, if your numbers have the same sign the answer is positive, but if the two numbers have different signs the answer is negative.

i think its all right took me awhile to find it though

Try Learn together, TSR's study area

38,252
revision notes

42,820
mindmaps

44,253
crosswords

15,911
quizzes

create
a study planner

thousands
of discussions

Today on TSR

### Need help with revision?

Check out our study tools and resources now.

### My mum and BFF's mum are having an affair

Poll
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE