# How to Calculate Percentages Easily

Calculating percentages is a basic skill that is useful in many aspects of both daily life and professional contexts. Whether it’s for calculating discounts, understanding statistics, or measuring changes over time, being able to work with percentages is an invaluable ability. In this article, we will go through four common percentage calculations and show you how you can easily master them.

## 1. **Find the Percentage of a Number**

A percentage shows how a number relates to 100. For example, if you want to find out what portion of a class wears glasses, you use this formula:

**Formula:** (Part / Whole) * 100%

**Example:** In a class of 20 students, 5 students wear glasses. To find the percentage of students with glasses, you calculate (5/20)×100%=25%. So, 25% of the students in the class wear glasses.

**2. Convert Percentage to Actual Value**

When you know the percentage and want to find the actual value it represents in a larger whole, you use this method:

**Formula:** (Percentage / 100) * Whole

**Example:** If 30% of the 40 students in a class have blue eyes, how do we find out how many there are? (30/100)×40=12. This means that 12 students have blue eyes.

## 3. **Find Percentage Change**

Percentage change is useful for comparing changes over time, such as in price, salary, or number.

**Formula:** ((New Value – Old Value) / Old Value) * 100%

**Example:** If a store had 150 customers last year and 180 this year, what is the percentage increase? (180−150)/150×100%=20%. The number of customers has increased by 20%.

**4. Calculate Value Change Based on Percentage**

This method is used when you know the percentage of change and want to calculate the actual value of the change.

**Formula:** (Percentage / 100) * Old Value

**Example:** An employee has a salary of 5000 NOK and gets a salary increase of 10%. How much is the salary increase? (10/100)×5000=500 NOK. The salary increase is 500 NOK.