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MATHEMATICSNumber & Arithmetic
CURRENT TOPICPercentages
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โ— Master Topic Guide Verified 11+ Curriculum

Percentages Master Guide ๐Ÿ“Š

Master percentage definitions, FDP conversions, finding percentage of amounts, reverse percentages, and bar model word problems for 11+ exams!

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PERCENTAGES OVERVIEW

A percentage means "out of 100". We write it using the % symbol. ($25\% = \frac25100 = 0.25$)

1. WHAT IS A PERCENTAGE?

A percentage shows a part of a whole "out of 100". The whole is 100%.

25%
โ• 25 out of 100
โ• 25/100 โ• 0.25
2. PERCENTAGE, FRACTION & DECIMAL

Percentages, fractions and decimals can show the same value.

PercentageFractionDecimal
1%1/1000.01
5%5/100 or 1/200.05
10%10/100 or 1/100.10
25%25/100 or 1/40.25
50%50/100 or 1/20.50
75%75/100 or 3/40.75
100%100/100 or 11.00
3. BAR MODEL & PIE CHART

Percentages can be shown in different visual ways.

25%
25%
25%
25%
โ–  75% shaded
โ–ก 25% not shaded
4. EQUIVALENT PERCENTAGES

Different percentages and fractions can be equivalent.

50% โ• 1/2 โ• 0.5 โ• 2/4 โ• 4/8
1/2
5. FINDING % OF AN AMOUNT
Formula: (% / 100) ร— Amount
10% of 80 โ• (10/100) ร— 80 โ• 8
25% of 60 โ• (25/100) ร— 60 โ• 15
50% of 90 โ• (50/100) ร— 90 โ• 45
75% of 40 โ• (75/100) ร— 40 โ• 30
5% of 200 โ• (5/100) ร— 200 โ• 10
6. FINDING THE WHOLE AMOUNT
Formula: Whole โ• (Part / %) ร— 100
20 is 25% of ? โž” (20/25)ร—100 โ• 80
15 is 30% of ? โž” (15/30)ร—100 โ• 50
36 is 60% of ? โž” (36/60)ร—100 โ• 60
7. PERCENTAGES GREATER THAN 100%

Percentages can be more than 100%. (150% means 150 out of 100 = 1.5)

120% โ• 1.2175% โ• 1.75250% โ• 2.5
Number Line: 0 โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€ 100% โ”€โ”€โ”€โ”€ 150% โ”€โ”€โ”€โ”€ 200%
8. REAL LIFE EXAMPLES
๐Ÿท๏ธ Sale: ยฃ50 shirt reduced 20% โž” 20% is ยฃ10 โž” Sale price ยฃ40
๐Ÿ”‹ Battery: 75% charged โž” 75 out of 100 parts charged
๐Ÿ“ Test score: 64 out of 80 โž” (64/80)ร—100 โ• 80%
๐Ÿ”„

EQUIVALENT FRACTIONS, DECIMALS & PERCENTAGES

Different ways to show the same value. Fractions, decimals and percentages are equivalent.

KEY IDEAS
  • โ˜… Equivalent means equal in value.
  • โ˜… Size is the same, just written differently.
  • โ˜… You can convert between all three!
EQUIVALENT FRACTIONS, DECIMALS & PERCENTAGES โ€“ QUICK REFERENCE TABLE
FRACTIONDECIMALPERCENTAGE
1/4
0.25
25%
25%
25%
25%
25%
1/2
0.50
50%
25%
25%
25%
25%
3/4
0.75
75%
25%
25%
25%
25%
1/1
1.00
100%
25%
25%
25%
25%
1/5
0.20
20%
25%
25%
25%
25%
2/5
0.40
40%
25%
25%
25%
25%
3/5
0.60
60%
25%
25%
25%
25%
4/5
0.80
80%
25%
25%
25%
25%
1/8
0.125
12.5%
25%
25%
25%
25%
3/8
0.375
37.5%
25%
25%
25%
25%
5/8
0.625
62.5%
25%
25%
25%
25%
7/8
0.875
87.5%
25%
25%
25%
25%
1/10
0.10
10%
25%
25%
25%
25%
FRACTION TO DECIMAL

1. Divide numerator by denominator.

3/4 โ• 3 รท 4 โ• 0.75
DECIMAL TO PERCENTAGE

1. Multiply decimal by 100.

0.75 ร— 100 โ• 75%
PERCENTAGE TO DECIMAL

1. Divide percentage by 100.

75% รท 100 โ• 0.75
PERCENTAGE TO FRACTION

1. Write percentage over 100.
2. Simplify the fraction.

75% โ• 75/100 โ• 3/4
COMMON EQUIVALENT FRACTIONS (USEFUL TO KNOW)
1/2 โ• 2/4 โ• 4/8
1/3 โ• 2/6 โ• 3/9
1/4 โ• 2/8 โ• 3/12
3/4 โ• 6/8 โ• 9/12
REMEMBER

โ˜… All three show the exact same amount!

โ˜… It's just a different way of writing it!

INTERACTIVE FDP GRID VISUALIZER

Hover over any grid to see its percentage representation!

50% (1/2)50% out of 100
25% (1/4)25% out of 100
10% (1/10)10% out of 100
75% (3/4)75% out of 100
20% (1/5)20% out of 100
1% (1/100)1% out of 100
๐Ÿ“Š

PERCENTAGE WORD PROBLEMS USING BAR MODELS

Bar models help us understand percentage problems by showing the whole as 100% and parts as equal sections.

1. FINDING A PERCENTAGE OF AN AMOUNT

Q: 25% of a number is 30. What is the number?

25% (30)
25% (30)
25% (30)
25% (30)

25% is 1/4 of the whole. If 25% = 30, then 100% = 30 ร— 4 = 120.

Answer: The number is 120.
2. FINDING THE WHOLE AMOUNT

Q: 60% of a number is 72. What is the number?

10%
10%
10%
10%
10%
10%
10%
10%
10%
10%

60% is 6 lots of 10%. 72 รท 6 = 12 (one lot of 10%). 100% = 12 ร— 10 = 120.

Answer: The number is 120.
3. FINDING A PART (PERCENTAGE)

Q: A bag has 80 sweets. 30% of the sweets are red. How many are red?

8
8
8
8
8
8
8
8
8
8

10% of 80 = 8. 30% = 3 lots of 10% = 8 ร— 3 = 24 sweets.

Answer: 24 sweets are red.
4. FINDING A PERCENTAGE

Q: In a class of 40 students, 16 students like pizza. What percentage likes pizza?

Each 10% block = 40 รท 10 = 4 students. 16 students = 4 lots of 10% = 40%.

Answer: 40% of the class likes pizza.
5. MULTI-STEP WORKING BACKWARDS

Q: Sam gives ยฃ30 to his sister, spends half of the rest on presents, and has ยฃ20 left. How much did he start with?

Work backwards: ยฃ20 left is half of remaining โž” remaining before presents = ยฃ40. Before ยฃ30 sister gift = ยฃ40 + ยฃ30 = ยฃ70.

Answer: Sam started with ยฃ70.
6. SALE DISCOUNT COMPARISON

Q: A jacket is ยฃ80. It is in a sale with 25% off. What is the sale price?

Whole 100% = ยฃ80. Discount 25% = ยฃ20. Sale price 75% = ยฃ80 โˆ’ ยฃ20 = ยฃ60.

Answer: The sale price is ยฃ60.
INTERACTIVE PERCENTAGES CHAMPION QUIZ11+ Exam Practice
1. Find 15% of 80:
2. If 20% of a number is 16, what is the number?
3. Reduce ยฃ50 by 20%:
4. 16 out of 40 students like pizza. What % is this?

๐Ÿš€ Ready to Test Your Knowledge?

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