Starter Questions

1. 76 - 54

2. Calculate 75% of 400

3. What is the name of the shape will this net make.

4. Calculate the value of the missing angle. 36o

Learning Intention

To explain how to divide by 20, 300, 4000 etc using our

knowledge so far.

Whole NumbersMultiply or Divide by 20,300,4000

Whole Numbers

Example 1 : Calculate 20 x 52

20 can be written as 2 x 10 so we have :

By combining our knowledge so far of “multiplying / dividing by 10, 100, 1000”

and “multiplying / dividing by a single digit”

we can do harder calculations.We use a TWO step process.

Multiply or Divide by 20,300,4000

2 x 10 x 52 =

Step 1 : 10 x 52 = Step 2 : 2 x 520 =520 1040

Whole Numbers

Example 2 : Calculate 44 x 30

30 can be written as 10 x 3 so we have :

Multiply or Divide by 20,300,4000

44 x 10 x 3 =

Step 1 : 44 x 10 = Step 2 : 440 x 3 =440 1320

Example 3 : Calculate 300 x 35

300 can be written as 3 x 100 so we have :3 x 100 x 35 =

Step 1 : 100 x35 = Step 2 : 3500 x 3 =3500 10500

Whole Numbers

Example 4 : Calculate 16000 ÷ 200

To divide by 200, divide by 100 then divide by 2:

Multiply or Divide by 20,300,4000

16000 ÷ 100 ÷ 2 =

Step 1 : 16000 ÷ 100 =

Step 2 : 160 ÷ 2 =

160

80

Whole Numbers

Example 5 : Calculate 120000 ÷ 6000

To divide by 6000, divide by 1000 then divide by 6:

Multiply or Divide by 20,300,4000

120000 ÷ 1000 ÷ 6 =

Step 1 : 120000 ÷ 1000 =

Step 2 : 120 ÷ 6 =

120

20

Now try Ex 8Ch1 page 19

Whole NumbersMultiply or Divide by 20,300,4000