Online Percentage Calculators

Online calculators to find the percentage of an amount, calculate discount, percentage increase, and more use cases. Learn how to calculate percentages with formulas and examples. Use period as decimal separator.

1. How much is A% of B

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100
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100
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2. What % is A of B

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100
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100 ·
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3. Discount of A% on B

-

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(100-)
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4. Increase of A% on B

+

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(100+)
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5. A is B% of a quantity

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100 ·
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6. Calculate A% from a known B%

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What is a Percentage?

A percentage is a way of representing a part or fraction of a whole in relation to 100. In other words, a percentage tells us how many parts of a whole are represented in terms of 100. For example, if we say that 25% of a cake has been consumed, we are indicating that one-quarter of the cake has been eaten.

The term "percentage" comes from the Latin "per centum," which means "per hundred." In mathematics, it is used to express a part of a whole in relative terms to a hundred. Therefore, a percentage is a way to represent proportions and compare different quantities. For example, if we say that 20% of a class passed an exam, we are expressing that out of every 100 students, 20 were successful.

How is a Percentage Calculated?

The calculation of percentages is based on the following formula, which has its roots in the rule of three in mathematics:

Percentage = Part/Total x 100
  • Part: The quantity considered as a part of the whole.
  • Total: The total quantity that includes the part.
  • Multiplied by 100 to express the result in terms of a percentage.

The rule of three is a mathematical principle that allows us to solve proportions. In this case, it helps us find how many times the part fits into the total in relation to 100. Let's look at an example: If you have a total of 200 items and want to know how many of them represent 20% of the total, you would use the formula. Here, the part would be 20, the total 200, and the result would be 10, as 20 is 10% of 200.

The formula is fundamental to understanding how parts relate to wholes and how to express that relationship in terms of a percentage. It is a powerful means to compare, assess, and make decisions based on proportions.

Solved Percentage Exercises

Percentage problems are a fundamental part of everyday life. Through these solved examples, you can understand how to apply percentages in everyday situations, from calculating discounts on purchases to determining salary increases. These exercises will provide you with the necessary tools to master the world of percentages and use them effectively in your personal and professional life.

Exercise 1

Statement: 20% of a number is equal to 40. What is that number?

Solution: To find the number, first convert the percentage to a decimal fraction (20% = 0.20). Then, divide 40 by 0.20: (40 / 0.20 = 200). Therefore, the number is 200.

Exercise 2

Statement: If 15% of a monthly salary is $450, what is the full monthly salary?

Solution: To find the full monthly salary, convert the percentage to a decimal fraction (15% = 0.15) and solve the equation (0.15x = 450), where "x" is the monthly salary. Divide both sides by 0.15 to get (x = 450 / 0.15 = 3000). Therefore, the full monthly salary is $3,000.

Exercise 3

Statement: A t-shirt with an original price of $40 has a 25% discount. How much does the t-shirt cost after the discount?

Solution: First, calculate the value of the discount. 25% of $40 is (0.25 * 40 = 10). Subtract that value from the original price: (40 - 10 = 30). So, the t-shirt costs $30 after the discount.

Exercise 4

Statement: A mobile phone is priced at $500, but it has increased by 15%. What is the new price?

Solution: To find the new price, first calculate the increase. 15% of $500 is (0.15 * 500 = 75). Then, add that value to the original price: (500 + 75 = 575). The new price is $575.

Exercise 5

Statement: If 30% of an unknown number is equal to 60, what is that number?

Solution: Similar to the first exercise, convert 30% to a decimal fraction (30% = 0.30) and solve the equation (0.30x = 60), where "x" is the unknown number. Divide both sides by 0.30 to get (x = 60 / 0.30 = 200). So, the number is 200.

What is the Purpose of Calculating a Percentage?

Percentages are essential tools in various aspects of our lives:

  • Comparison and Evaluation: They allow us to compare and evaluate relationships between different quantities on a common scale, facilitating informed decision-making.
  • Discounts and Offers: Percentages are used in discounts and offers, helping us save money when purchasing products or services at reduced prices.
  • Personal Finance: In the financial domain, percentages are applied to interest rates, investments, mortgages, and loans, enabling us to better understand our finances and make intelligent decisions.
  • Business and Marketing: Companies use percentages in pricing strategies, promotions, and sales analysis to attract customers and increase profits.

Applications of Percentage in Everyday Life

Percentages are found in a variety of everyday situations:

  • Shopping Discounts: Discounts in stores and online are expressed in percentages, allowing us to know how much we can save on our purchases.
  • Tax Calculation: Taxes on sales, income, and property are applied as percentages of the respective values.
  • Savings and Loans: Banks use interest rates in percentages for savings and loan accounts, affecting our savings and debts.
  • Statistics and Data Analysis: Percentages are used in surveys, market reports, and data analysis to understand trends and patterns.
  • Health and Nutrition: The percentages of ingredients on food and beverage labels help us make healthy choices.

Percentages are an essential mathematical tool used in various contexts in our everyday lives. Understanding what percentages are, how they are calculated, and what they are used for enables us to make informed decisions, save money, and better comprehend the world around us. Whether in shopping, personal finance, business, or statistics, percentages are fundamental to our understanding and decision-making.