Percentage — From Zero to Hero
✨ IN SHORT — THE WHOLE LESSON IN 20 SECONDS
Percentage simply means 'out of 100'. If you can divide anything into 100 equal parts, you already understand percentage. This one lesson will make all percentage questions easy.
1. What is Percentage?
Percentage = a fraction with denominator 100. 25% means 25 out of 100, i.e. 25/100 = 1/4. To change any fraction into percentage, multiply by 100. To change percentage into a number, divide by 100. Example: 40% of 200 = (40/100) × 200 = 80.
📌 Example: In a class of 50 students, 30 are girls. Girls = 30/50 × 100 = 60%.
2. The Golden Fraction Table (memorise this!)
1/2=50%, 1/3=33.33%, 1/4=25%, 1/5=20%, 1/6=16.66%, 1/8=12.5%, 1/10=10%, 1/20=5%. Most exam questions are built on these 8 fractions. Learn them like your phone number.
💡 Trick: x% of y = y% of x. So 36% of 50 = 50% of 36 = 18. Choose whichever side is easier!
3. Percentage Increase & Decrease
Increase % = (Increase ÷ Original) × 100. Decrease % = (Decrease ÷ Original) × 100. Always divide by the ORIGINAL (starting) value — this is the number-1 mistake students make.
📌 Example: Price rises from ₹80 to ₹100. Increase = 20. Increase% = 20/80 × 100 = 25% (not 20%!).
4. Successive Percentage Change
If a value changes by a% then b%, total change = a + b + (ab/100). For decrease, use negative sign. Two discounts of 20% and 10% = -20 -10 + (200/100) = -28%. So the real discount is 28%, not 30%.
💡 Trick: + then − of the SAME % is always a LOSS of (x²/100)%. Price +10% then −10% = 1% loss. Exam favourite!
⚡ Now Practise — 10 Questions
Tap an answer. Right or wrong, we explain why instantly. Learn from every tap!
Q1. What is 25% of 640?
Q2. A number increases from 50 to 65. What is the percentage increase?
Q3. Two successive discounts of 10% and 10% equal a single discount of:
Q4. If 40% of a number is 120, the number is:
Q5. A price is increased by 20% then decreased by 20%. Final result?
Q6. 75% written as a fraction in simplest form is:
Q7. In an exam, 60% of 750 candidates passed. How many failed?
Q8. What percent of 2 hours is 30 minutes?
Q9. If A's salary is 25% more than B's, B's salary is what % less than A's?
Q10. A student scores 360 out of 500. His percentage is:
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