How to Calculate Percentage: Calculator and Simple Formula

✨ Quick Answer: How to Calculate Percentage

Formula: (Your Number ÷ Total) × 100

4 Easy Steps:

1. Find your number and the total

2. Divide your number by the total

3. Multiply by 100

4. Add the % symbol

📌 Example:

If you want to calculate the percentage of 25 out of 50

Step 1: Your number = 25, Total = 50
Step 2: 25 ÷ 50 = 0.5
Step 3: 0.5 × 100 = 50
Step 4: 50% ✅

What is a Percentage?

A percentage is a way to express a number as a part of 100. The word "percent"
means "per hundred" or "out of 100."

Simple Example: If you score 75 out of 100 on a test, you scored 75 percent
(75%).

Percentages help us:

• Compare different numbers easily

• Understand discounts when shopping

• Calculate test scores and grades

• Track business growth or losses

• Understand interest rates on loans

The Basic Percentage Formula (Simple Explanation)

The formula to calculate any percentage is:

Percentage = (Your Number ÷ Total) × 100

What does this mean?

• Your Number = What you got or have (the smaller number)

• Total = The maximum or full amount (the bigger number)

• ÷ = Divide (same as /) - split into parts

• × = Multiply (same as *) - make bigger

How to Calculate Percentage: Step-by-Step Guide

Method 1: Calculate What Percent X is of Y

Question: What percent is 30 out of 120?

Step 1: Identify the numbers

Your number = 30 (what you have)
Total = 120 (the maximum)

Step 2: Divide your number by the total

30 ÷ 120 = 0.25

Step 3: Multiply by 100

0.25 × 100 = 25

Step 4: Add the % symbol

Answer: 25% ✅

Method 2: Find X% of a Number

Question: What is 20% of 250?

Step 1: Convert percentage to decimal

20 ÷ 100 = 0.20

Step 2: Multiply by the number

0.20 × 250 = 50

Answer: 50 ✅

This means 20% of 250 equals 50

Method 3: Calculate Percentage Increase or Decrease

Question: A price increased from $100 to $125. What is the percentage
increase?

Step 1: Find the difference

New Price - Old Price = $125 - $100 = $25

Step 2: Divide by the original number

$25 ÷ $100 = 0.25

Step 3: Multiply by 100

0.25 × 100 = 25

Answer: 25% increase ✅

Formula for percentage change:

Percentage Change = ((New Value - Old Value) ÷ Old Value) × 100

Real-Life Examples of Percentage Calculations

Example 1: Shopping Discount

Scenario: A shirt costs $80. The store offers a 30% discount. How much will
you save?

Solution:

1. Convert 30% to decimal: 30 ÷ 100 = 0.30

2. Multiply: 0.30 × $80 = $24

3. You save: $24

4. Final price: $80 - $24 = $56

Example 2: Test Score

Scenario: You answered 42 questions correctly out of 50. What is your
percentage score?

Solution:

1. Your number = 42, Total = 50

2. Divide: 42 ÷ 50 = 0.84

3. Multiply: 0.84 × 100 = 84

4. Your score: 84%

Example 3: Salary Increase

Scenario: Your salary increased from $3,000 to $3,450. What percentage did
it increase?

Solution:

1. Find difference: $3,450 - $3,000 = $450

2. Divide by original: $450 ÷ $3,000 = 0.15

3. Multiply by 100: 0.15 × 100 = 15

4. Salary increased by: 15%

Example 4: Tax Calculation

Scenario: A meal costs $45. Tax is 8%. How much is the tax?

Solution:

1. Convert 8% to decimal: 8 ÷ 100 = 0.08

2. Multiply: 0.08 × $45 = $3.60

3. Tax amount: $3.60

4. Total bill: $45 + $3.60 = $48.60

Common Mistakes to Avoid

❌ Mistake 1: Forgetting to Multiply by 100

Wrong: 25 ÷ 50 = 0.5 (This is not the percentage!)

Right: 25 ÷ 50 = 0.5, then 0.5 × 100 = 50%

❌ Mistake 2: Mixing Up Part and Whole

Question: What percent is 20 out of 80?

Wrong: 80 ÷ 20 = 4 (This is backward!)

Right: 20 ÷ 80 = 0.25, then 0.25 × 100 = 25%

❌ Mistake 3: Percentage Change Confusion

Important: A 10% increase followed by a 10% decrease does NOT bring you back to the original number.

Example:

• Start: $100

• 10% increase: $100 × 1.10 = $110

• 10% decrease of $110: $110 × 0.90 = $99 (not $100!)

Quick Tips for Fast Percentage Calculations

💡 Mental Math Shortcuts

10% of any number: Just move the decimal point one place left

• 10% of 350 = 35

• 10% of 89 = 8.9

50% of any number: Divide by 2

• 50% of 80 = 40

• 50% of 150 = 75

25% of any number: Divide by 4

• 25% of 100 = 25

• 25% of 200 = 50

1% of any number: Move the decimal point two places left

• 1% of 500 = 5

• 1% of 1,200 = 12

When to Use Percentage Calculations

Percentages are used in many everyday situations:

• Shopping: Calculate discounts and sales prices

• Education: Understand test scores and grades

• Finance: Calculate interest rates, loan payments, and investment returns

• Business: Track profit margins, growth rates, and market share

• Health: Monitor weight loss, body fat percentage, and nutrition values

• Statistics: Understand data, polls, and survey results

• Cooking: Adjust recipe quantities

• Tips: Calculate restaurant tips (15%, 18%, 20%)

Practice Problems (Try These!)

Test Your Skills:

Problem 1: What percentage is 18 out of 60?

Show Answer

18 ÷ 60 = 0.30 → 0.30 × 100 = 30%

Problem 2: What is 15% of 200?

Show Answer

15 ÷ 100 = 0.15 → 0.15 × 200 = 30

Problem 3: A price decreased from $50 to $40. What is the percentage decrease?

Show Answer

Difference: $10 → $10 ÷ $50 = 0.20 → 0.20 × 100 = 20% decrease

Problem 4: You got 85 out of 100 on a test. What's your percentage?

Show Answer

85 ÷ 100 = 0.85 → 0.85 × 100 = 85%

Conclusion

Calculating percentages is a simple but powerful skill. Once you understand the
basic formula (Part ÷ Whole) × 100, you can use it in countless situations.

Remember the 4 steps:

1. Find your number and the total

2. Divide your number by the total

3. Multiply by 100

4. Add the % symbol

Use the free calculator above to practice and check your answers. With regular
practice, you'll be able to calculate percentages quickly in your head!

📚 Quick Reference Card

Basic Formula: (Your Number ÷ Total) × 100

Finding X% of Y: (X ÷ 100) × Y

% Change: ((New - Old) ÷ Old) × 100