Mathematical operations with percentages can be confusing because they are a different type of numerical representation. Percentages, based on a scale of 100, represent a portion of a given value --- like 10 percent of 50 is 5. Decimals work with a smaller scale, with the numbers trailing the decimal point ranging from less than one to greater than zero. By changing a percentage's representation to an equivalent decimal, you create a form better suited for quick and simple math.
Instructions
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1
Write down the percentage. For this example, let the percentage be 20.5 percent.
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2
Strip the percentage of its percent sign -- 20.5 percent becomes 20.5.
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3
Add a decimal point to the right end of the number if it doesn't already have one -- 20.5 already has a decimal so no added point is need; if the percentage had been 20 percent, the number would become 20.0.
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Move the decimal two places to the left -- 20.5 becomes 0.205.