DIRECTED NUMBERS

Objectives: Add, subtract, multiply and divide directed numbers

Grade 8

Monica Roshani Rupasinghe

Directed Numbers

👉Numbers which has a direction as

well a size are called directed numbers.

👉They can be negative or positive

👉 Positive + sign

Negative - sign

Visualising negatives with a number line

-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6

For any addition/subtraction of numbers, you should ALWAYSvisualise a number line. How would we visualise the following?

Click>

Click>

Click>

Click>

Eg 1 : Temperature starts at 4°C & falls by 4°C

Eg 2 : Temperature starts at -2°C & rise by 5°C

Exercise1 ( e3 pg 52 / e4 pg 58 / e5 pg 56 )

Exercise1 ( e3 pg 52 / e4 pg 58 / e5 pg 56 )

Addition & Subtraction 👉 If the signs are SAME , we add the numbers ( +,+ or -,-)

👉 If the signs are DIFFERENT , we Subtract the numbers

✅ Subtract the smaller number by larger number

✅ Sign in front of the Larger number is the sign of the result

Example

Test Your Understanding

Copy and complete the following.

What is ?

a

b

c

d

e

f

g

h

N

???

?????

?

Multiplication & Division

👉 If the signs are SAME , the result is Positive

👉 If the signs are DIFFERENT , the result is Negative

📌 Division

📌 Multiplication

Example

Use of Brackets

Adding/subtracting negative numbers

What is the answer. How could we show it?

What is the answer. How could we show it?

✏

Quick fire Examples

1. ?

?

?

?

?

?

?

RED ORANGE GREEN BLUE

Use your diary coloured cards to vote for the correct answer in each question.

(Use the front of your diary for blue)

Calculate:

Calculate:

Calculate:

Calculate:

Calculate:

Calculate: