When we say "Percent" we are really saying "per 100"
One percent (1%) means 1 per 100.
1% of this line is shaded green: it is very small isn't it?
 | 50% means 50 per 100
(50% of this box is green) |
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25% means 25 per 100
(25% of this box is green) |  |
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Examples:
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100% means all.
Example:
100% of 80 is 100100 × 80 = 80
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50% means half.
Example:
50% of 80 is 50100 × 80 = 40
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5% means 5/100ths.
Example:5% of 80 is
5100 × 80 = 4So 75% really means
75100
And 100% is 100100, or exactly 1 (100% of any number is just the number, unchanged)
And 200% is 200100, or exactly 2 (200% of any number is twice the number)
A Percent can also be expressed as a Decimal or a Fraction
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| A Half can be written... | |
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| As a percentage: |
50%
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| As a decimal: |
0.5
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| As a fraction: |
1/2
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Some Worked Examples
Example: Calculate 25% of 80
25% = 25100
And 25100 × 80 = 20
So 25% of 80 is 20
Example: 15% of 200 apples are bad. How many apples are bad?
15% = 15100
| And 15100 × 200 | | = 15 × 200100 |
| | | = 15 × 2 |
| | | = 30 apples |
30 apples are bad
Example: if only 10 of the 200 apples are bad, what percent is that?
As a fraction, 10200 = 0.05
As a percentage it is: 10200 x 100 = 5%
5% of those apples are bad
Example: A Skateboard is reduced 25% in price in a sale.
The old price was $120.
Find the new price.
First, find 25% of $120:
25% = 25100
And 25100 × $120 = $30
25% of $120 is $30
So the reduction is $30
Take the reduction from the original price
$120 − $30 = $90
The Price of the Skateboard in the sale is $90
Calculation Trick
This little rule can make some calculations easier:
x% of y = y% of x
Example: 8% of 50
8% of 50 is the same as 50% of 8
And 50% of 8 is 4
So 8% of 50 is also 4
The Word
"Percent" comes from the latin Per Centum. The latin word Centum means 100, for example a Century is 100 years.
Percent vs Percentage
My Dictionary says "Percentage" is the "result obtained by multiplying a quantity by a percent". So 10 percent of 50 apples is 5 apples: the 5 apples is the percentage.
But in practice people use both words the same way.
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