What is percentage calculation?
A percentage expresses a number as a fraction of 100. In everyday work, percentages describe discounts, tax rates, growth, tips, and commissions. This tool focuses on three common patterns: finding a percent of a value (basic), applying a percentage increase, and applying a percentage decrease.
How percentage increase works
To increase a value by a given percent, multiply the original value by one plus the percentage expressed as a decimal. For example, increasing 100 by 20% uses the factor 1.20, giving 120. The difference (here, 20) is the absolute increase compared with the original amount.
How percentage decrease works
To decrease a value by a given percent, multiply the original value by one minus the percentage as a decimal. Decreasing 100 by 15% uses the factor 0.85, giving 85. The difference (15) is how much was removed relative to the starting value.
Examples
- Basic: 25% of 200 is 50.
- Increase: A price of 80 with a 10% increase becomes 88 (an increase of 8).
- Decrease: A budget of 500 reduced by 30% becomes 350 (a reduction of 150).
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