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Academy11+

💰 Percentages of Amounts

Learn to find percentages of amounts. Master the methods for calculating parts of whole numbers and solve real-world percentage problems.

Intermediate Level
40-50 minutes
Percentage Calculations

What are Percentages of Amounts?

Percentages of amounts help us find parts of whole numbers! 💰

Finding percentages of amounts means calculating what part of a whole number a percentage represents. This is essential for discounts, taxes, interest rates, and many real-world calculations.

Basic Method
Convert and multiply

Convert percentage to decimal, then multiply by the amount. Example: 20% of £50 = 0.2 × £50 = £10

Mental Math
Quick calculations

Use mental math for common percentages. 10% = divide by 10, 5% = half of 10%, 1% = divide by 100.

Real Applications
Everyday uses

Used for discounts, sales tax, tips, interest rates, and many other real-world calculations.

Key Concepts

Basic Method

Convert percentage to decimal, then multiply by the amount. This is the most reliable method for all calculations.

Mental Math

Use shortcuts for common percentages. 10% = divide by 10, 5% = half of 10%, 1% = divide by 100.

Real Applications

Used for discounts, sales tax, tips, interest rates, and many other everyday calculations.

Detailed Examples

Example 1: Basic Method

Find: 20% of £50

Convert 20% to decimal
20% = 0.2
Multiply by amount
0.2 × £50 = £10
Answer: £10

Basic Method Steps

• Convert percentage to decimal
• Multiply by the amount
• Check your answer makes sense
• Add currency symbol if needed
• Always check your answer

Example 2: Mental Math

Find: 15% of 80

Find 10% first
10% of 80 = 8
Find 5% (half of 10%)
5% of 80 = 4
Add: 8 + 4 = 12
Answer: 12

Mental Math Shortcuts

• 10% = divide by 10
• 5% = half of 10%
• 1% = divide by 100
• 50% = half
• 25% = quarter

Example 3: Real Application

Discount: 25% off £120

Find 25% of £120
25% = 0.25
0.25 × £120 = £30
Discount = £30
Final price = £120 - £30 = £90
You save: £30

Discount Calculation

• Find percentage of original price
• Subtract from original price
• Or multiply by (100% - discount%)
• Check your answer makes sense
• Always check your answer

Interactive Activities

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Activity 1: Percentage Calculator

Calculate percentages of different amounts.

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Activity 2: Mental Math

Practice quick mental calculations.

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Activity 3: Shopping Discounts

Calculate discounts and sale prices.

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Activity 4: Percentage Quiz

Test your percentage skills.

Practice Questions

Practise this with a free account

4 practice questions on this topic, from easy to 11+ level. Reading the guide is free for everyone; practice is for members, and signing up is free.

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Tips and Tricks

Mental Math Shortcuts

  • • 10% = divide by 10
  • • 5% = half of 10%
  • • 1% = divide by 100
  • • 50% = half
  • • 25% = quarter

Basic Method

  • • Convert percentage to decimal
  • • Multiply by the amount
  • • Check your answer makes sense
  • • Add currency symbol if needed
  • • Always check your answer

Real Applications

  • • Discounts and sales
  • • Sales tax calculations
  • • Tips and gratuities
  • • Interest rates
  • • Commission calculations

Memory Tricks

  • • "Convert, then multiply"
  • • "10% = divide by 10"
  • • "5% = half of 10%"
  • • "50% = half"
  • • "Always check your answer"