Calculating a percentage involves finding a proportion of a number in relation to the whole, often expressed as a fraction of 100. Here are a few common methods to calculate percentages:
1. Percentage of a Number:
To find a certain percentage of a number, multiply the number by the percentage and divide by 100.
Example: What is 20% of 150?
(20/100) * 150 = 0.2 * 150 = 30
So, 20% of 150 is 30.
2. Percentage Increase or Decrease:
To calculate the percentage increase or decrease between two numbers, use the following formula:
((New Value - Old Value) / Old Value) * 100
((Old Value - New Value) / Old Value) * 100
3. Percentage of a Whole:
To find what percentage one number is of another, divide the part by the whole and multiply by 100.
Example: What percentage is 40 of 200?
(40 / 200) * 100 = 0.2 * 100 = 20%
4. Percentage Points:
When discussing changes in percentages, it’s important to understand the concept of percentage points. A percentage point is the arithmetic difference between two percentages. For example, an increase from 20% to 30% is a 10 percentage point increase.
5. Calculating Discounts or Markups:
To calculate the final price after a discount or markup, you can use the following formulas:
Final Price = Original Price - (Original Price × Discount Percentage / 100)
Final Price = Original Price + (Original Price × Markup Percentage / 100)
Understanding these basic methods will allow you to calculate percentages in various situations. Excel and most calculators also have built-in functions to simplify these calculations.