Percentages — Simple Guide

What is a Percentage?

Percent means per 100. For example, 25% means 25 out of 100 (0.25).

Conversions

  • Fraction → %: multiply by 100 (eg. 1/4 = 25%)
  • Decimal → %: multiply by 100 (eg. 0.75 = 75%)
  • % → Fraction/Decimal: divide by 100 (eg. 40% = 0.4)

Key Formulas

Value (percentage of number):
Value = (Percentage × Total) / 100
Percentage change:
% Change = (Difference / Original) × 100
Find total from value:
Total = (Value × 100) / Percentage

Where percentages are used

Profit & Loss
Discounts
Simple Interest
Exam Marks
Price Changes

Shortcuts

  • Increase by x% → multiply by 1 + x/100
  • Decrease by y% → multiply by 1 - y/100
  • Successive % changes x and y → net % = x + y + (x·y)/100

Interactive examples

Result:
No calculation yet

Percentages — 20 Practice Questions

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  1. 1. What is 25% of 200?
  2. 2. Convert 0.45 to a percentage.
  3. 3. What is 150 as a percentage of 300?
  4. 4. Increase 80 by 20%.
  5. 5. Decrease 250 by 10%.
  6. 6. If 30 is 15% of a number, what is the number?
  7. 7. Convert 3/5 to a percentage.
  8. 8. A price rises from 120 to 150. What is the percentage increase?
  9. 9. What is 12.5% of 400?
  10. 10. If a student scores 162 out of 180, what is the percentage?
  11. 11. Find the net % change when increase 10% then increase 20%.
  12. 12. What is the percentage form of 7/8?
  13. 13. A shirt is marked ₹800 and sold at 25% discount. Sale price?
  14. 14. If VAT is 12% on ₹500, how much VAT is paid?
  15. 15. What percent of 250 is 75?
  16. 16. Convert 0.037 to percentage.
  17. 17. If a population falls from 10,000 to 9,200, what is the percentage decrease?
  18. 18. Find x if x% of 500 = 125.
  19. 19. What is 5% of 360?
  20. 20. A bank gives 8% simple interest per year. What interest on ₹1,000 after 2 years?

Tip: Try solving on paper before revealing the answer.