How do you calculate a precentage?

Any number can be converted to a percentage by multiplying it by 1, but we do this in a special way. Since 1 =100/100 or 100%, if we multiply anything by 1, although its appearance may change its valua remains the same.

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So let's take a decimal number first.

Strictly speaking a decimal should be called a decimal fraction.

To change 0.085 to a percentage we do .085 x 100/100, but we write it down this way: 0.085 x 100%

To do the multiplication by 100 bit we simply move the decimal point 2 places to the right.

That gives us 8.5, but don't forget the % sign.

The correct answer is 0.085 = 8.5%

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Now for a fraction. Let is take 5/8

So the calculation is 5/8 x 1 = 5/8 x 100/100 = 5/8 x 100% = 5 x 100%/8

By cancelling the 100 and the 8 by 4 we get 5 x 25%/2 = 125%/2 = 62.5%

Remember that when you multiply by 1 in that special way you do not change the value, only the appearance; and don't forget the % sign.