© T Madas. What do we find when we calculate: 50% of a number? We are finding one half of that number 25% of a number? We are finding a quarter of that

© T Madas

© T Madas

What do we find when we calculate:

50% of a number?

50% = 50100

12=

We are finding one half of that number

25% of a number?

25% = 25100

14=

We are finding a quarter of that number

© T Madas

What do we find when we calculate:

10% of a number?

10% = 10100

110=

We are finding one tenth of that number

15% of a number?

15% = 15100

320=

We are finding three twentieths of that number

© T Madas

to find 10%

What is 10% of 70?

What is 10% of 150?

What is 10% of 65?

70 ÷ 10 =

150 ÷ 10 =

65 ÷ 10 =

we must remember when we calculate percentageswe find

110

we divide by 10

7

15

6.5

to find 5% we divide by 10

find 10% first

5% is half of 10%we half the last

answer

What is 5% of 40?

What is 5% of 60?

What is 5% of 150?

40 ÷ 10 = 4

60 ÷ 10 = 6

150 ÷ 10 = 15

4 ÷ 2 = 2

6 ÷ 2 = 3

15 ÷ 2 = 7.5

© T Madas

to find 1%

What is 1% of 600?

What is 1% of 1100?

What is 1% of 250?

What is 1% of 40?

600 ÷ 100 =

1100 ÷ 100 =

250 ÷ 100 =

40 ÷ 100 =

we must remember when we calculate percentageswe find

1100

we divide by 100

6

11

2.5

0.4

© T Madas

10% :

5% :

1% :

Find 20% of 80

10% = 8

20% = 2 x 8

=16

Find 30% of 60

10% = 6

30% = 3 x 6= 18

Divide by 10

Divide by 10

Divide by 100

and then half the answer

© T Madas

Find 40% of 70

10% = 7

40% = 4 x 7

=28

Find 60% of 40

10% = 4

60% = 6 x 4= 24

10% :

5% :

1% :

Divide by 10

Divide by 10

Divide by 100


© T Madas

Find 15% of 60 Find 35% of 80

10% = 65% = 3

15% =30% = 245% = 4

35% =

10% = 8

10% :

5% :

1% :

Divide by 10

Divide by 10

Divide by 100


9

28

© T Madas

Find 45% of 40

40% = 165% = 2

45% =

10% = 4

Find 65% of 120

60% = 725% = 6

65% =

10% = 12

10% :

5% :

1% :

Divide by 10

Divide by 10

Divide by 100


18 78

© T Madas

+1%+5%+10%+10%+10%10%46% =

+1%+1%+10%+10%10%32% =

+1%+5%10%16% =

How do we find 16%, 32% or 46% ?

10% :

5% :

1% :

Divide by 10

Divide by 10

Divide by 100


© T Madas

Find 16% of 280

5% = 141% =

16% =

10% = 28

Find 36% of 120

5% = 61% = 1.2

16% =

10% = 12

30% = 36

10% :

5% :

1% :

Divide by 10

Divide by 10

Divide by 100


2.43

2.88.44

© T Madas

PercentagePractice

© T Madas

What is 10% of 80?What is 20% of 30?What is 30% of 40?What is 40% of 50?What is 50% of 36?

What is 60% of 70?

What is 70% of 30

What is 80% of 60? What is 90% of 200?What is 20% of 35?

8

3x 2 =

6

4x 3 =12

5 x 4 =

20

36÷ 2 =

18

7 x 6 = 42

3 x 7 =

21

6 x 8 = 48

20 x 9 =180

3.5x 2 =7

Calculating Percentages Mentally

© T Madas

What is 10% of 110?What is 20% of 150?What is 30% of 120?

What is 40% of 90?What is 50% of 50?

What is 60% of 30?

What is 70% of 40


11

15 x 2 =

30

12x 3 =36

9 x 4 =

36

50÷ 2 =

25

3 x 6 =18

4 x 7 =

28

9 x 8 =72

30 x 9 =270

4.5 x 2 = 9


© T Madas

What is 10% of 60?What is 15% of 80?What is 35% of 60?What is 45% of 120?What is 25% of 300?What is 65% of 200?What is 40% of 125?What is 16% of 300? What is 12% of 200?What is 16% of 50?

6

8+4= 12

6+6+6+3=

21

12+12+12+12

+6= 54

30+30+15=

75

20x 6+10=130

12.5+12.5+12.5+12.5=

50

30

+15+3=48

20+2+2=

24

5+2.5

+0.5=

8


© T Madas

What is 10% of 90?What is 15% of 60?What is 35% of 80?What is 45% of 40?What is 25% of 200?What is 65% of 300?What is 20% of 125?What is 16% of 400? What is 12% of 150?What is 16% of 250?

9

6+3=9

8+8+8+4=28

4+4+4+4+2=18

20+20+10=

50

30x 6+15=195

12.5+12.5=25

40

+20+4=64

15+1.5+1.5=18

25+12.5+2.5=

40


© T Madas

Test onPercentages

© T Madas

Test on Calculating Percentages MentallyWhat is 10% of

80?What is 20% of 30?What is 30% of 40?What is 40% of 50?What is 50% of 36?

What is 60% of 70?

What is 70% of 30


8

3x 2 =

6

4x 3 =12

5 x 4 =

20

36÷ 2 =

18

7 x 6 = 42

3 x 7 =

21

6 x 8 = 48

20 x 9 =180

3.5x 2 =7

© T Madas


110?What is 20% of 150?What is 30% of 120?

What is 40% of 90?What is 50% of 50?

What is 60% of 30?

What is 70% of 40


11

15 x 2 =

30

12x 3 =36

9 x 4 =

36

50÷ 2 =

25

3 x 6 =18

4 x 7 =

28

9 x 8 =72

30 x 9 =270

4.5 x 2 = 9

© T Madas


60?What is 15% of 80?What is 35% of 60?What is 45% of 120?What is 25% of 300?What is 65% of 200?What is 40% of 125?What is 16% of 300? What is 12% of 200?What is 16% of 50?

6

8+4= 12

6+6+6+3=

21

12+12+12+12

+6= 54

30+30+15=

75

20x 6+10=130

12.5+12.5+12.5+12.5=

50

30

+15+3=48

20+2+2=

24

5+2.5

+0.5=

8

© T Madas


90?What is 15% of 60?What is 35% of 80?What is 45% of 40?What is 25% of 200?What is 65% of 300?What is 20% of 125?What is 16% of 400? What is 12% of 150?What is 16% of 250?

9

6+3=9

8+8+8+4=28

4+4+4+4+2=18

20+20+10=

50

30x 6+15=195

12.5+12.5=25

40

+20+4=64

15+1.5+1.5=18

25+12.5+2.5=

40

© T Madas

Fill inPercentageTables

© T Madas

3921936153060

65%35%15%5%10%25%50%

16812084080200400800

21%15%1%5%10%25%50%

78453153075150300

26%15%1%5%10%25%50%

© T Madas

52281248204080

65%35%15%5%10%25%50%

1057552550125250500

21%15%1%5%10%25%50%

1569063060150300600

26%15%1%5%10%25%50%

© T Madas

6349217143570140

45%35%15%5%10%25%50%

37.8271.89184590180

21%15%1%5%10%25%50%

57.2222.2112255110220

26%15%1%5%10%25%50%

© T Madas

14411248163280160320

45%35%15%5%10%25%50%

92.4664.42244110220440

21%15%1%5%10%25%50%

6537.52.512.52562.5125250

26%15%1%5%10%25%50%

© T Madas

Quick Test in FillingPercentageTables

© T Madas

3921936153060

65%35%15%5%10%25%50%

16812084080200400800

21%15%1%5%10%25%50%

78453153075150300

26%15%1%5%10%25%50%

© T Madas

52281248204080

65%35%15%5%10%25%50%

1057552550125250500

21%15%1%5%10%25%50%

1569063060150300600

26%15%1%5%10%25%50%

© T Madas

6349217143570140

45%35%15%5%10%25%50%

37.8271.89184590180

21%15%1%5%10%25%50%

57.2222.2112255110220

26%15%1%5%10%25%50%

© T Madas

14411248163280160320

45%35%15%5%10%25%50%

92.4664.42244110220440

21%15%1%5%10%25%50%

6537.52.512.52562.5125250

26%15%1%5%10%25%50%

© T Madas

© T Madas

Find of 350

Find 12% of 350

12

100

Find of 400

Find 37% of 400

400 ÷ 100

= 4

4 x 37 = 14837

100

Calculating Percentages in General

350 ÷ 100= 3.5

3.5 x 12 = 42

© T Madas

Find of 850


Find 45% of 850

45

100 850 = 382.545

100´

Find of 125

Find 24% of 125

24

100 125 = 3024

100´

850 ÷ 100= 8.5

8.5 x 45 = 382.5

125 ÷ 100

= 1.25

1.25 x 24 = 30

© T Madas

Find of 473


Find 19% of 473

19

100 473 = 89.8719

100´

Find of 24

Find 17.5% of 24

17.5

100 24 = 4.217.5

100´

473 ÷ 100

= 4.73

4.73 x 19 = 89.87

24 ÷ 100

= 0.24

0.24 x 17.5 = 4.2

© T Madas

0 . EXP Ans =

1 2 3 + –

4 5 6 x ÷

7 8 9 DEL AC

RCL ENG ( ) , M+

(–) . , ,, hyp sin cos tan

a b/c x2 log ln

x-1 nCr Pol(

REPLAY

^

^^

^

SHIFT ALPHA MODE ON

x! nPr Rec( 3

x3

d/c 10xx ex

^sin-1 cos-1 tan-1

M-

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STO

π DRG› %Rnd Ran#

A B C D E F

X Y M;

e

:

CLR

CalculatorPracticewith

Percentages

© T Madas

Find 12% of 140 16.8

Find 34% of 185 62.9

Find 22% of 387 85.14

Find 35% of 96.4 33.74

Find 72% of 855 615.6

Find 41% of 390 159.9

Find 26% of 307 79.82

Find 9% of 110 9.9

Calculator Practice with Percentages

Find 12.5% of 68 8.5

Find 17.5% of 240 42

Find 8.5% of 384 32.64

Find 27.5% of 120 33

Find 7.2% of 855 61.56

Find 16.4% of 365 59.86

Find 1.7% of 300 5.1

Find 0.5% of 110 0.55

© T Madas

Find 14% of 160 22.4

Find 35% of 284 99.4

Find 24% of 749 179.76

Find 45% of 146.4 65.88

Find 32% of 855 273.6

Find 11% of 930 102.3

Find 36% of 385 138.6

Find 7% of 220 15.4

Find 12.5% of 88 11

Find 17.5% of 320 56

Find 8.5% of 384 32.64

Find 27.5% of 360 99

Find 8.2% of 900 73.8

Find 18.4% of 565 103.96

Find 0.5% of 360 1.8

Find 0.25% of 400 1


© T Madas

0 . EXP Ans =

1 2 3 + –

4 5 6 x ÷

7 8 9 DEL AC

RCL ENG ( ) , M+

(–) . , ,, hyp sin cos tan

a b/c x2 log ln

x-1 nCr Pol(

REPLAY

^

^^

^

SHIFT ALPHA MODE ON

x! nPr Rec( 3

x3

d/c 10xx ex

^sin-1 cos-1 tan-1

M-

OFF

STO

π DRG› %Rnd Ran#

A B C D E F

X Y M;

e

:

CLR

CalculatorTestwith

Percentages

© T Madas

Find 12% of 140 16.8

Find 34% of 185 62.9

Find 22% of 387 85.14

Find 35% of 96.4 33.74

Find 72% of 855 615.6

Find 41% of 390 159.9

Find 26% of 307 79.82

Find 9% of 110 9.9


Find 12.5% of 68 8.5

Find 17.5% of 240 42

Find 8.5% of 384 32.64

Find 27.5% of 120 33

Find 7.2% of 855 61.56

Find 16.4% of 365 59.86

Find 1.7% of 300 5.1

Find 0.5% of 110 0.55

© T Madas

Find 14% of 160 22.4

Find 35% of 284 99.4

Find 24% of 749 179.76

Find 45% of 146.4 65.88

Find 32% of 855 273.6

Find 11% of 930 102.3

Find 36% of 385 138.6

Find 7% of 220 15.4

Find 12.5% of 88 11

Find 17.5% of 320 56

Find 8.5% of 384 32.64

Find 27.5% of 360 99

Find 8.2% of 900 73.8

Find 18.4% of 565 103.96

Find 0.5% of 360 1.8

Find 0.25% of 400 1


© T Madas

© T Madas

Marcus bought a shirt and a pair of trousers in the July sales.The shirt costs normally £18 but it was 20% off in the sales.The trousers cost normally £25 but it was 10% off in the sales.How much did he have to pay for the two items?

20% of £18 is £3.60

£18 – £3.60 = £14.40

10% of £25 is £2.50

£25 – £2.50 = £22.50

10% of £18 is £1.80

14.40+ 22.50

36.90£

© T Madas

© T Madas

Ann is a gorilla that weighs 185 kg.

Her mate, Ben weighs 18% more than Ann.

How many kg does Ben weigh?

Ann Ben

185 kg +18%

Find 18% of 185185 ÷ 100

= 1.851.85 x

18 = 33.3185 +

33.3 = 218.3 kg

© T Madas

© T Madas

1. Express the weight of Albert as a percentage of the weight of Bernard.

2. How many times bigger is Bernard than Albert?

Albert and Bernard are the two pet dogs shown.Albert weighs 32 kg and Bernard weighs 50 kg.

Albert Bernard

32 kg 50 kg

Albert’s weight

Bernard’s weight

= 3250

= 64%64100

=

Albert’s weight is 64% of Bernard’s weight

Bernard’s weight

Albert’s weight

= 5032

= 1.5625

Bernard is 1.5625 times bigger than Albert

© T Madas

© T Madas

Fraction

0.25

0.08

0.22

0.45

Decimal

25%Other

8%Indian

22%Chinese

45%Pizza

PercentageFood

600 people were asked for their preferred take-away food.The results were summarised in a table:

1. Complete the table.2. Work out how many people preferred an Indian take-away.

14

25100=

920

45100=

1150

24100=

225

8100=

8% 8 out of 10016 out of 20024 out of 300 . . . . . . . .48 out of 600

© T Madas

© T Madas

What is 12.5% of 48% as a percentage?

Finding something of something always means

multiplication

© T Madas

What is 12.5% of 48% as a percentage?

12.5100

48100

x = 60010000

6100

= = 6%

method 1

0.125 0.48x =0.06= 6%

method 2

method 3

50%25%

12.5%

= ½= ¼= ⅛

Finding 12.5% of 48% …… is the same as finding ⅛ of 48% …… i.e. 6%

12.5%48%

= 0.125= 0.48

© T Madas

© T Madas

Which out of:… 20% of £150 or 150% of £20 …… is the largest?

20% of £150: £15

x 2 = £30

150% of £20: £20

+ = £30 £10

100% 50%

© T Madas

© T Madas

Look at the table of information about A level passes in 2006.

How many more students gained grade A in English than in Maths?

35%27%Percentage gained grade A

4800084000Number of students

MathematicsEnglish

8400010027

x 22680=

4800010035

x 16800=

5880

84000 ÷ 100 = 840

840 x 27 = 22680

48000 ÷ 100 = 480

480 x 35 = 16800

22680 – 16800 = 5880

or in fraction notation

© T Madas

Documents

© T Madas. What do we find when we calculate: 50% of a number? We are finding one half of that number 25% of a number? We are finding a quarter of that