Percentage (Intro) — Class 5 IMO

Meaning of Percent & Conversions

Percent means 'out of 100'. So 50% means 50 out of 100, which equals ½ or 0.5.

To change a fraction or decimal to a percentage, multiply by 100 (¼ = 25%, 0.3 = 30%). To change a percentage to a fraction or decimal, divide by 100 (20% = 20/100 = ⅕ = 0.2).

Example 1: Write ½ as a percentage.

½ × 100 = 50%.

Example 2: Write 0.3 as a percentage.

0.3 × 100 = 30%.

Quick recap

Percent means out of 100.
Fraction/decimal to % : multiply by 100; % to fraction/decimal: divide by 100.

✓ Quick check

Write 25% as a fraction in simplest form.

25% = 25/100 = ¼.

Write ¾ as a percentage.

¾ × 100 = 75%.

Percentage of a Number

To find a percentage of a number, change the percentage to a fraction or decimal, then multiply. For example, 25% of 80 = (25/100) × 80 = 20.

A quick way: 10% of a number is found by dividing by 10, so 10% of 200 = 20.

Example 1: Find 50% of 60.

Half of 60 = 30.

Example 2: Find 20% of 50.

(20/100) × 50 = 10.

Quick recap

Percentage of a number: change % to a fraction/decimal, then multiply.
10% of a number = the number ÷ 10.

✓ Quick check

What is 10% of 90?

90 ÷ 10 = 9.

What is 25% of 200?

(25/100) × 200 = 50.

Percentage in Real Life

Percentages appear in discounts and marks. A 20% discount on ₹500 means ₹100 off (so you pay ₹400). Scoring 45 out of 50 means (45/50) × 100 = 90%.

Example 1: A ₹500 item has a 20% discount. How much is taken off?

20% of 500 = ₹100 off.

Example 2: A student scores 45 out of 50. What percentage is that?

(45/50) × 100 = 90%.

Quick recap

Discount = percentage of the price taken off.
Marks percentage = (score ÷ total) × 100.

✓ Quick check

A ₹200 item has a 10% discount. How much is taken off?

10% of 200 = ₹20.

A student scores 18 out of 20. What percentage is that?

(18/20) × 100 = 90%.