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Mental maths · lesson 14 of 28 · free

How to calculate percentage — Mental Maths Mastery

Four percentages cover most shopping and marks questions. 10% is a tenth, 50% is a half, 25% is a quarter and 5% is half of 10%. Build every answer from these.

▶ Watch how it works

Got it? Practise ↓

How to do it in your head

Tenth, half, quarter — “10% ÷ 10, 50% half, 25% half of half, 5% half of 10%”

  1. 10%: divide by 10.
  2. 5%: find 10%, then halve it.
  3. 50%: halve. 25%: halve, then halve again.

Use it for: Discounts in a sale, tips, marks in a test, and interest on savings.

🧮 Check your own sums with the free Percentage calculator — it shows the working.

Worked example: 25% of ₹340 = 85

  1. 25% is half of a half.
  2. Half of 340 = 170.
  3. Half of 170 = 85.

Check: 85 × 4 = 340 ✓

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✓ Written and checked by the TalentJR team · Updated 13 Oct 2026 · How we make our lessons

✏️ Practice

Work it out in your head or on paper, then tap your answer — or type it and press Check. Stuck? Press “Show me how”.

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🏁 Lesson 14 test

20 questions. Check each answer, then go to the next one. Get 16 or more right to pass.

🏅 Sign in with Google to earn the 🏷️ Discount Detective badge when you pass — and a certificate when you finish all 6 lessons of Part 3 · Mental maths for daily life. You can still take the test without signing in.

🖨️ Percentage Worksheet for Class 6 and 7

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