A percentage is a way of writing a fraction with a denominator of 100.
Percentage means "out of 100" or "per hundred"
Calculations involving percentages often require multiplication or division by 100.
x percent, written x%, means x⁄100 (or x parts out of 100)
| Write 40% as a fraction |
40% = 40⁄100 = 20⁄50 = 10⁄25 = 2⁄5 |
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Write the fraction 7⁄10 as a percentage |
70% |
Percentage Calculations
Below are some of the types of problem that use percentages.
Percentage of a quantity:
To find x percent of a quantity. Calculate: x⁄100 × (the quantity)
|
Find 8% of 300 |
300 × 8⁄100 = 24 |
One quantity as a percentage of another quantity:
To find a out of b as a percentage. Calculate: a⁄b × 100⁄1
|
Write 13 out of 20 as a percentage. |
13⁄20 × 100⁄1 = 65% |
Increasing a quantity by a percentage:
To increase a quantity by x percent. Calculate: 
|
Increase 50 by 8% |
|
Decreasing a quantity by a percentage:
To decrease a quantity by x percent. Calculate: 
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Decrease 50 by 8% |
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