## How to Calculate Percentages in Standard American English

Percentages are a common way to express proportions or ratios. They are used in a variety of contexts, such as math, science, finance, and everyday life. Understanding how to calculate percentages is an important skill that can help you make sense of the world around you.

**What is a Percentage?**

A percentage is a fraction expressed as a hundredth. It is written using the symbol %, which means "per hundred." For example, 50% means 50 per hundred, or 50/100.

**Calculating Percentages**

There are two main methods for calculating percentages:

**Using a calculator:**Most calculators have a percentage key that can be used to calculate percentages. To use the percentage key, simply enter the number you want to find the percentage of, followed by the percentage sign (%). For example, to find 50% of 100, you would enter 100 * 50% = 50.**Using the formula:**The formula for calculating percentages is:

`percentage = (part / whole) * 100`

For example, to find 50% of 100, you would use the formula:

`percentage = (50 / 100) * 100`

`percentage = 50%`

**Converting Percentages to Decimals**

Percentages can be converted to decimals by dividing the percentage by 100. For example, to convert 50% to a decimal, you would divide 50 by 100:

`50% / 100 = 0.5`

**Converting Decimals to Percentages**

Decimals can be converted to percentages by multiplying the decimal by 100. For example, to convert 0.5 to a percentage, you would multiply 0.5 by 100:

`0.5 * 100 = 50%`

**Applications of Percentages**

Percentages are used in a wide variety of applications, including:

**Math:**Percentages are used to solve a variety of math problems, such as finding the percentage of change, the average of a set of numbers, and the slope of a line.**Science:**Percentages are used to express the concentration of solutions, the purity of chemicals, and the efficiency of machines.**Finance:**Percentages are used to calculate interest rates, loan payments, and investment returns.**Everyday life:**Percentages are used to express the likelihood of events, the progress of projects, and the satisfaction of customers.

**FAQ**

**What is the difference between a percentage and a fraction?**

A percentage is a fraction expressed as a hundredth, while a fraction is a more general term for a part of a whole.

**How do I find the percentage of one number to another?**

To find the percentage of one number to another, use the formula:

`percentage = (part / whole) * 100`

For example, to find the percentage of 50 to 100, you would use the formula:

`percentage = (50 / 100) * 100`

`percentage = 50%`

**How do I find the percentage of change from one number to another?**

To find the percentage of change from one number to another, use the formula:

`percentage change = ((new value - old value) / old value) * 100`

For example, to find the percentage change from 100 to 150, you would use the formula:

`percentage change = ((150 - 100) / 100) * 100`

`percentage change = 50%`

**How do I use percentages to calculate discounts and markups?**

- To calculate a discount, use the formula:

`discount = (list price - sale price) / list price * 100`

- To calculate a markup, use the formula:

`markup = (sale price - cost) / cost * 100`