Percentages are one way to represent the relationship between a portion and the whole. Common uses for percentages include calculating the portion of sales an employee is responsible for, the portion of strikes a pitcher throws or the portion of questions a student gets correct on a test. Using percentages allows you to compare different ratios because the percentage is always out of 100, so all percentages have a common denominator.

Identify the quantity of the part and the quantity of the whole. For example, if you wanted to determine what percentage of a company’s sales came from a particular employee, the sales that employee generated would be the part and the total company sales would be the whole.

Divide the part by the whole. In this example, if the employee generated $45,000 of sales and the company as a whole did $400,000, divide $45,000 by $400,000 to get 0.1125.

## Sciencing Video Vault

Multiply 100 by the Step 2 result to find the percentage. In this example, multiply 0.1125 by 100 to find the employee was responsible for 11.25 percent of the company’s sales.