Percentages

# Percentages

A percentage is a special type of fraction with 100 as the denominator. Percentage is indicated by the symbol %.

How to write a percentage as a fraction

To write a percentage as a fraction you write using 100 as the denominator.

Example: 35% is written as 35100.

How to change a fractions as a percentage

To change a fraction to a percentage you multiply by 100.

Example: 25 written as a percentage = 25 × 100 = 40%

How to change a decimal to a percentage

To change a decimal to a percentage you multiply by 100.

Example: 0.63 = 0.63 × 100 = 63%

How to write a percentage as a decimal

To write a percentage as a decimal you must divide by 100.

Example: 35% = 35100 = 0.35

Percentage Calculation

Example: Find 35% of 200.

35% of 200 means 35% × 200

= 35100 × 200

= 70

How to express one quantity as a percentage of another

Example Express 54 as a percentage of 60.

= 5460 × 100 = 90%

Finding percentage increase

percentage increase = increaseoriginal amount × 100

Example: The number of students in a grade 10 class was increased from 20 to 25. Find the percentage increase.

Solution

original amount = 20

increase = 25 - 20 = 5

% increase = 520 × 100 = 25%

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