Percentage Basics

Easy

A percentage expresses a number as a fraction of 100.

Why It Matters

Percentages appear in data interpretation, profit/loss, and salary comparisons — nearly every placement aptitude test includes them.

How It Works

A percentage is a way of expressing a number as a fraction of 100. To convert a fraction to a percentage, multiply by 100. To convert a percentage to a decimal, divide by 100. Key formulas: Percentage = (Part / Whole) × 100. Percentage change = ((New − Old) / Old) × 100. When a value increases by x% and then decreases by x%, the net result is always a decrease of (x²/100)%.

Example

If a shirt's price increases from ₹400 to ₹500, the percentage increase = ((500 − 400) / 400) × 100 = 25%.

Common Mistakes

Students often calculate percentage change using the new value as the base instead of the old value. Another common error is assuming successive percentage changes cancel out (e.g., +20% then −20% ≠ 0%).

Test Your Understanding

Easy Q1

A shopkeeper increases the price of an item from ₹800 to ₹1000. What is the percentage increase?

Easy Q2

If 30% of a number is 45, what is 50% of that number?

Easy Q3

In an election, candidate A gets 60% of votes. If A wins by 2,400 votes, what is the total number of votes?

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Related Concepts

Profit and Loss

Profit and loss calculations determine the gain or deficit from a transaction based on cost price and selling price.

Time and Work

Time and Work problems relate the rate of work of individuals or groups to the total time taken to complete a task.

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