LI: To find a percentage of an amount

S.C:

. I can use fractional equivalences to find a percentage of an amount.

. I can use bar models to help organise my solutions.

. I can choose a preferred method to finding a percentage of an amount.

Fractions and Percentages

Key equivalents you need to know:

50% =

25% =

75% =

10% =

1

2

1

4

3

4

1

10

Percentages of Amounts

Calculate 50% of 60

50% = 1

2

1

2of 60 = 60 ÷ 2

= 30

Find 50% of 246

Percentages of Amounts

Calculate 25% of 60

25% = 1

4

1

4of 60 = 60 ÷ 4

= 15

Find 25% of 460

Percentages of Amounts

Calculate 10% of 60

10% = 1

10

1

10of 60 = 60 ÷ 10

= 6

Find 10% of 450

Percentages of Amounts

Calculate 20% of 60

First calculate 10%

10% = 60 ÷ 10

= 6

If 10% = 6, then 20% = 6 x 2 = 18

Find 20% of 360

Percentages of Amounts

Calculate 30% of 260

First calculate 10%

10% = 260 ÷ 10

= 26

If 10% = 26, then 30% = 26 x 3 = 78

Find 30% of 620

Percentages of Amounts

Calculate 5% of 400

First calculate 10%

10% = 400 ÷ 10

= 40

5% is half of 10%

10% = 40 so 5% = 20

Find 5% of 240

Percentages of Amounts

Calculate 15% of 800

First calculate 10%

10% = 800 ÷ 10

= 80

5% = half of 10% = 40

15% = 10% + 5% = 80+40 = 120

Find 15% of 240

Percentages of Amounts

Calculate 15% of 60

First calculate 10%

10% = 60 ÷ 10 = 6

5% = 3

15% = 9

Can you calculate:

15% of 4800

Now find 35% of 1200

Now find 35% of 2460

Finding 75% of amounts

Finding 75% of amounts:

To find 1%

1% of 540 = ?

Always divide the number by 100 to find 1%

540 ÷ 1 = 5.4

Ben and Sam have a bag containing 48 sweets. Whilst watching a film they eat 75% of the sweets. How many sweets are left?

There are 300 pupils in a school and 75% of the pupils are boys. How many girls are there in the school?