The three percentage questions
Almost every percentage problem is one of three: finding a percentage of a number (what is 15% of 8,000?), finding what percentage one number is of another (what percent of 8,000 is 1,200?), and finding the percentage change between two values (a salary rising from 80,000 to 92,000). The tool covers each.
Formulas
- X% of Y = X ÷ 100 × Y
- Percent = part ÷ whole × 100
- Change % = (new − old) ÷ old × 100
Everyday uses in Pakistan
Students convert marks to a percentage for admissions, shoppers check sale discounts, employees work out the effect of an increment, and business owners add GST or calculate margins. For example, a 17% GST on Rs 10,000 adds Rs 1,700. A fall from Rs 120 to Rs 90 is a 25% decrease, but going back from 90 to 120 is a 33.3% increase, because the base differs.
For tax-related percentages see the income tax calculator.
Worked examples
| Question | Working | Answer |
|---|---|---|
| 15% of Rs 8,000 | 15 / 100 x 8,000 | Rs 1,200 |
| Rs 1,200 is what % of Rs 8,000 | 1,200 / 8,000 x 100 | 15% |
| Salary from Rs 80,000 to Rs 92,000 | (92,000 - 80,000) / 80,000 x 100 | 15% increase |
| Price Rs 2,500 after 20% discount | 2,500 x 0.80 | Rs 2,000 |
| Marks 412 out of 550 | 412 / 550 x 100 | 74.9% |
Percentages in daily life
- Shopping: work out the real price after discount and compare shops.
- Exams: convert marks to a percentage for admission aggregates.
- Business: add sales tax or compute a margin with the profit calculator.
- Finance: compare interest and returns with the ROI calculator.
Percentage points vs percent
If a rate rises from 10% to 12%, it has gone up by 2 percentage points but by 20% in relative terms. News about interest rates and inflation often mixes these up. Use the percent-change mode when you need the relative change.
See also the income tax calculator, GPA calculator and zakat calculator, which all rely on percentages.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100.
How do I find percentage increase?
Subtract the old value from the new value, divide by the old value and multiply by 100.
Why is a 20% rise followed by a 20% fall not back to the start?
The second percentage applies to a larger base, so the result is 4% lower than the original.
How do I add GST to a price?
Multiply the price by 1 plus the GST rate. For 18% GST, multiply by 1.18.