Percentages are everywhere — from shopping discounts to interest rates to test scores. Here are practical examples of percentage calculations you'll use in real life.
Finding a Percentage of a Number
To find X% of a number, multiply by X/100.
What is 15% of 200? 200 × 0.15 = 30
Calculating Discounts
When shopping, you often need to calculate the sale price after a discount.
A $80 shirt is 25% off. Discount = 80 × 0.25 = $20 Sale price = 80 - 20 = $60
Use our free Discount Calculator for instant sale price calculations.
Percentage Change
To calculate the percentage increase or decrease between two values:
Change = ((New - Old) / Old) × 100 Example: Price went from $40 to $50. Change = ((50-40)/40) × 100 = 25% increase
Tip Calculation
Calculating a tip is a common percentage use case:
- •15% tip on $45: 45 × 0.15 = $6.75
- •18% tip on $60: 60 × 0.18 = $10.80
- •20% tip on $35: 35 × 0.20 = $7.00
Test Score Percentage
To find what percentage you scored on a test:
You got 42 out of 50 questions correct. Percentage = (42/50) × 100 = 84%
Quick Mental Math Tricks
- •To find 10%: move the decimal one place left (10% of 250 = 25)
- •To find 5%: find 10% and halve it (5% of 250 = 12.5)
- •To find 20%: find 10% and double it (20% of 250 = 50)
- •To find 1%: move the decimal two places left (1% of 250 = 2.5)
Use our free Percentage Calculator for all your percentage needs.