Understanding how to calculate percentages is an essential skill that has practical applications in everyday life and different professions. Whether you are calculating a sale discount, determining the tax amount on a purchase or analyzing data, knowing how to calculate percentages correctly is important.

This article will provide you with a step-by-step guide, tips, and tricks on how to find the percentage of two numbers correctly. You will also learn about common mistakes to avoid, the importance of understanding percentages and how to use technology for accurate calculations.

A Step-by-Step Guide to Calculating Percentages

Before we delve into how to calculate percentages accurately, let us first define what a percentage is.

Definition of Percentage

A percentage is a way of expressing one number as a fraction or a decimal of another number, typically represented by a percent sign (%). It tells you how many parts of a whole or total amount you have, with 100% being the total amount.

Formula for Calculating Percentages

The general formula for calculating percentages is:

Percent (%) = (Part / Whole) x 100

The part represents the smaller number, while the whole represents the larger number. To find the percentage, divide the part number by the whole number, then multiply by 100.

Step-by-Step Breakdown of the Process

Let us break down the formula into steps for easier understanding:

  1. Identify the whole and part numbers
  2. Divide the part number by the whole number
  3. Multiply the result by 100
  4. Add the percentage sign (%)

Examples to Help Readers Understand the Process

Here are some examples of how to apply the formula:

  • Example 1: What is 15% of 200?
  • Solution:

    Whole = 200, Part = ? (15% of 200)

    (Part / Whole) x 100 = %

    (Part / 200) x 100 = 15%

    Cross multiply to solve for part:

    Part x 100 = 15 x 200

    Part = (15 x 200) / 100

    Part = 30

    Therefore, 15% of 200 is 30.

  • Example 2: What is 20% off $50?
  • Solution:

    Whole = $50, Part = 20%

    Formula: Whole Amount x (1- Percentage Discount)

    $50 x (1 – 20%) = $40

    Therefore, the discount amount is $10.

    The final price after the discount is $40.

Tips for Quickly Calculating Percentages

Calculating percentages can be time-consuming sometimes, but with a few tips, you can quickly find the percentage of two numbers.

Use of Mental Math

Mental math is an excellent tool for finding percentages quickly. Instead of calculating the percentage using the formula, you can use mental math by breaking down the numbers into easier fractions.

For example, to find 25% of 160, you can quickly calculate it by halving the number twice: 160/2 = 80, 80/2 = 40. Therefore, 25% of 160 is 40.

Rounding up or Down for Easier Calculations

Rounding up or down is another way to quickly calculate percentages. This is best used when you don’t need an exact answer.

For example, to calculate 15% of 83, you can round 83 down to 80. Then calculate 10% of 80 by moving the decimal one place to the left, which is 8. Finally, add half of 8, which is 4, to get 12. Therefore, 15% of 83 is approximately 12.

Breaking Numbers into Simpler Fractions

Another mental math trick is to break down numbers into easier fractions. For example, to calculate 16% of 175, you can break 16% down to 1/6. Therefore, 16% of 175 is the same as finding 1/6 of 175, which is 29.16 (175 รท 6).

Common Mistakes to Avoid When Calculating Percentages

Although calculating percentages is easy, there are common mistakes that people make. Here are some of the mistakes and ways to avoid them.

Misunderstanding the Percent Sign

The percentage symbol (%) is widely used, and it is easy to misinterpret it as a simple division symbol. Remember, the percentage sign means that you are working with parts of a whole number, and you need to multiply the result by 100.

Confusing Decimal with Percentage

Another mistake is confusing a decimal with a percentage. A decimal represents a fraction of a whole, while a percentage is a ratio of two numbers represented by a percent sign.

For example, 0.5 is a decimal that represents half of a whole, while 50% represents the ratio of 50 parts out of 100. Therefore, you cannot substitute a decimal for a percentage.

Incorrectly Calculating the Percentage Change

The percentage change is used to determine an increase or decrease in a value over time. The formula to calculate the percentage change is:

Percentage Change = ((New Value – Old Value) / Old Value) x 100%

One common mistake is to forget to include the old value when calculating the percentage change.

The Importance of Understanding Percentages

Understanding percentages is beneficial in different industries and professions.

Examples of Situations Where Understanding Percentages is Important

Here are some examples of where percentages are important:

  • Finance: Banks and financial institutions use percentages to calculate interest rates, loan amounts and mortgage rates.
  • Medicine: Doctors and healthcare professionals use percentages to monitor vital statistics such as blood pressure, heart rate and cholesterol levels.
  • Sales: Sales professionals use percentages to calculate commissions, discounts and profit margins.
  • Data Analysis: Data analysts use percentages to make sense of large data sets and to identify trends.

Benefits of Understanding Percentages

Understanding percentages can help you in many ways such as:

  • Calculation of discounts, sales tax and tips accurately
  • Better understanding of market trends
  • Monitoring personal health and fitness levels
  • Making informed financial decisions
  • More effective problem-solving abilities

Using Technology to Calculate Percentages

Technology has made it easier than ever to calculate percentages accurately in real-time. There are different technology tools available for calculating percentages.

Benefits of Using Technology

Using technology to calculate percentages saves time and ensures that your calculations are accurate. Different technology tools have unique benefits that make the calculations even easier.

Drawbacks of Using Technology

One main drawback of using technology to calculate percentages is that it can be over-reliant on technology. This can lead to a decreased ability to perform calculations when technology is not available.

Different Technology Tools Available for Calculating Percentages

Here are some technology tools and applications that you can use to calculate percentages:

  • Calculator: Most smartphones come with a built-in calculator that you can use to calculate percentages.
  • Excel: You can use Excel to perform complex calculations such as percentages, graphs and charts.
  • Google Sheets: It is a cloud-based spreadsheet application with capabilities similar to Excel.
  • Percentage Calculator: There is a wide range of online percentage calculators that you can use to calculate percentages quickly.
  • Mathway: Mathway is a math problem solver application that can calculate percentages and solve other math problems.

Examples of Each Tool and How to Use Them

Here are some examples of how to use each tool to calculate percentages:

  • To use the calculator application on your smartphone, go to the calculator app, enter the part and the whole numbers, then multiply by 100.
  • In Excel, you can use formulas such as “=B1/B2” to calculate percentages.
  • In Google Sheets, you can use the same formulas used in Excel.
  • To use an online percentage calculator, go to the website, enter the part and the whole numbers, and the tool will calculate the percentage for you.
  • To use Mathway, go to the website, enter the math problem, and the application will solve it for you.


In conclusion, calculating percentages is an essential skill that can help you in many ways. With this step-by-step guide, you can now calculate percentages accurately and quickly using different tips and tricks.

Remember to avoid common mistakes such as misunderstanding the percentage sign and confusing decimal with percentage. Using technology can also help you to perform calculations correctly.

We hope that this article has provided you with a comprehensive guide on how to calculate percentages accurately, and you will also appreciate the importance of understanding percentages in different industries.

Now, it’s your turn to start practicing calculating percentages.

By Riddle Reviewer

Hi, I'm Riddle Reviewer. I curate fascinating insights across fields in this blog, hoping to illuminate and inspire. Join me on this journey of discovery as we explore the wonders of the world together.

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