Percentage Calculator: 10 Real-Life Uses You Face Every Week
The Three Percentage Questions
Every percentage problem is one of three types:
- What is X% of Y? = Y × X/100
- X is what % of Y? = (X/Y) × 100
- X is Y% of what? = X / (Y/100)
10 Real-Life Uses
| Situation | Formula | Example |
|---|---|---|
| Shop discount | Original × (1 − discount%/100) | ₹5,000 at 30% off = ₹3,500 |
| Salary hike | Salary × hike%/100 | ₹50K × 15% = ₹7,500 raise |
| GST/VAT | Price × (1 + rate%/100) | ₹1,000 + 18% GST = ₹1,180 |
| Tip in restaurant | Bill × tip%/100 | $50 × 20% = $10 tip |
| Profit margin | (Profit/Revenue) × 100 | (₹20K profit / ₹1L) × 100 = 20% |
| Exam score | (Marks/Total) × 100 | (72/90) × 100 = 80% |
| Interest rate | Principal × rate/100 × time | ₹10K × 8% × 1 = ₹800 |
| Population growth | Base × (1 + rate/100)^years | Compound growth over time |
| Commission earned | Sales × commission%/100 | ₹5L sales at 2% = ₹10,000 |
| Weight loss % | ((Start−Current)/Start) × 100 | (80-74)/80 × 100 = 7.5% |
Mental Math Shortcuts
- 10%: Move decimal one place left (₹850 → ₹85)
- 5%: Half of 10% (₹85 → ₹42.5)
- 25%: Divide by 4
- 15% tip: 10% + 5% (₹85 + ₹42.5 = ₹127.50)
- 1%: Move decimal two places left
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Open Percentage Calculator →Frequently Asked Questions
How do I calculate percentage increase?
% increase = (New Value − Old Value) / Old Value × 100. Example: salary increased from ₹40,000 to ₹46,000 = (6,000/40,000) × 100 = 15% increase.
What is the percentage off formula?
Sale price = Original price × (1 − discount%). Or find discount amount: Original × discount%, then subtract. ₹2,000 × 25% off: ₹500 off, so ₹1,500 final price.
How to find what percentage one number is of another?
Divide the part by the whole and multiply by 100. 45 out of 60 = (45/60) × 100 = 75%.