

Percentage Formula, Tricks & Common Mistakes
The concept of how to calculate percentage plays a key role in mathematics and is widely applicable to both real-life situations and exam scenarios. Whether it’s finding the percentage of marks, discounts in shopping, or increases in statistics, understanding percentages makes everyday calculations easier and faster.
What Is How to Calculate Percentage?
A percentage is a way to express a number as a part of 100. It is denoted by the symbol “%”. For example, 25% simply means 25 out of 100. You’ll find this concept applied in areas such as calculating scores (“marks percentage”), measuring growth or decline (“percentage increase or decrease”), and comparing quantities in finance or shopping offers (“percentage discount”).
Key Formula for How to Calculate Percentage
Here’s the standard formula:
\( \text{Percentage (\%)} = \frac{\text{Part or Value}}{\text{Total Value}} \times 100 \)
Cross-Disciplinary Usage
How to calculate percentage is not only useful in Maths but also plays an important role in Physics, Computer Science, and daily logical reasoning. Students preparing for JEE, NEET, NTSE, and other competitive exams will often solve problems requiring quick percentage calculations. You’ll also see percentage questions in commerce, business, and even statistics topics.
Step-by-Step Illustration
- Identify the required values. Example: You scored 45 marks out of a total of 60 in a test.
Obtained Value = 45, Total Value = 60 - Apply the percentage formula:
Percentage = (45 / 60) × 100 - Calculate the division:
45 ÷ 60 = 0.75 - Multiply by 100:
0.75 × 100 = 75% - Final Answer: Your percentage is 75%
Working With Decimals and Fractions
Percentages can also be written as decimals and fractions. For example:
- To convert a decimal to percent: Multiply by 100. Example: 0.2 × 100 = 20%
- To convert a fraction to percent: Divide numerator by denominator, then multiply by 100. Example: 3/4 = 0.75, then 0.75 × 100 = 75%
How to Calculate Percentage Change
Use this when a quantity increases or decreases:
Percentage Change = \(\frac{\text{New Value} - \text{Original Value}}{\text{Original Value}} \times 100\)
For increase, this gives a positive result, and for decrease, a negative one.
Speed Trick or Vedic Shortcut
Here’s a quick trick: To find 10% of any number, move the decimal one place left. Example: 10% of 450 = 45. For 5%, take half of 10%. Example: 5% of 450 = 22.5. These shortcuts help in exams and in quick mental calculations.
Example Trick: To quickly find 30% of 300, just calculate 10% (30), then multiply by 3: 30 × 3 = 90.
Try These Yourself
- Find the percentage of 18 out of 24.
- Calculate what percent 45 is of 90.
- If the price of an item increased from ₹200 to ₹220, what is the percentage increase?
- Convert 0.62 into a percentage.
Frequent Errors and Misunderstandings
- Forgetting to multiply by 100 after dividing the values.
- Using the wrong base (total) value in the formula.
- Misplacing decimal points or making calculation mistakes under time pressure.
- Mixing up percent change and percent of—remember each has its own formula.
Relation to Other Concepts
The idea of how to calculate percentage connects closely with Percentage, Fraction to Percent, and Profit and Loss. Mastering percentages helps you understand ratios, proportions, data interpretation, and important competitive maths topics. For more detailed word problems and practice, explore Percentage Word Problems.
Classroom Tip
To remember the percentage formula, think: “Part divided by Total, then ×100.” Drawing a pie chart or using grid visuals in class can help students picture what a percentage means. Vedantu’s teachers often explain with daily life examples—like exam marks, shopping bills, or cricket scores—for better understanding.
We explored how to calculate percentage—from definition, formula, step-by-step examples, tricks, common mistakes, and its links to other maths topics. Practice often and review real-world scenarios to become confident in using this essential skill. For live help or detailed video sessions, Vedantu provides extra resources and tips!
FAQs on How to Calculate Percentage Step by Step
1. What is the formula for calculating percentage?
The basic percentage formula is: Percentage (%) = (Part / Whole) × 100. This means you divide the part by the whole and multiply the result by 100 to express it as a percentage.
2. How do I calculate the percentage increase or decrease?
To calculate percentage change, use this formula: Percentage Change = [(New Value - Original Value) / Original Value] × 100. A positive result indicates an increase, while a negative result shows a decrease.
3. How do I calculate the percentage of marks obtained in an exam?
Use the formula: Percentage of Marks = (Marks Obtained / Total Marks) × 100. For example, if you scored 75 out of 100, your percentage is (75/100) × 100 = 75%.
4. How can I calculate a percentage discount?
The formula for percentage discount is: Percentage Discount = (Discount Amount / Original Price) × 100. For instance, a $20 discount on a $100 item represents a (20/100) × 100 = 20% discount.
5. How to calculate percentage in Microsoft Excel?
In Excel, if the value is in cell A1 and the total is in cell B1, the formula is: =A1/B1*100. Remember to format the cell as a percentage after entering the formula.
6. What is 25% of 80?
To find 25% of 80, multiply 80 by 0.25 (the decimal equivalent of 25%): 80 × 0.25 = 20.
7. What are some common mistakes students make when calculating percentages?
Common errors include:
- Incorrectly placing the decimal point when converting decimals to percentages or vice versa.
- Using the wrong value as the whole in the percentage formula.
- Forgetting to multiply by 100 in the final step.
8. How do I calculate the percentage difference between two numbers?
The formula for percentage difference is: Percentage Difference = |(Number 1 - Number 2) / [(Number 1 + Number 2) / 2]| × 100. The absolute value ensures a positive result.
9. Can a percentage be negative?
Yes, a percentage can be negative, indicating a decrease or loss. For example, a -10% change signifies a 10% decrease.
10. How do I calculate percentage in real-life situations like calculating tips or sales tax?
Use the basic percentage formula: Percentage = (Part / Whole) x 100. For tips, the part is the tip amount, and the whole is the bill total. For sales tax, the part is the tax amount, and the whole is the pre-tax price.
11. What are some real-world applications of percentages besides those mentioned above?
Percentages are used extensively in various fields, including:
- Finance (interest rates, returns on investments)
- Science (data representation, experimental results)
- Statistics (describing proportions and distributions)
- Everyday life (calculating discounts, understanding proportions in recipes).

















