1. Subtract the earliest date's sales in dollars from the most current sales figures to find the dollar amount of growth. For instance, company A sold $100 worth of goods in 1995
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Sales tax is different in almost every state, but to calculate tax on a purchase you simply take the full purchase price and multiply it by the amount of tax in your area.
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((current month's sales  last month's sales)/last month's sales)x100
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1. Obtain data that shows a change in a quantity over time. All you need to calculate a basic growth rate are two numbers  one that represents a certain quantity's starting value
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