​Percent

• ​Parts per 100

• The symbol is %

• It tells you a ratio "out of 100"

​Percent Increase

The difference between a new value and an old value, expressed as a percentage of the old value, with the new value being larger than the old value

​Percent Decrease

The difference between a new value and an old value, expressed as a percentage of the old value, with the new value being smaller than the old value

​Percent Error

​The percent error is the absolute value of the error divided by the accepted value and multiplied by 100%.

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​Tax

​Money that the government collects based on income, sales, and other activities.

​Markup

​How much a retailer increases the price over what they paid for it (which is how they make money to pay for all their costs and hopefully make a profit).Shown as an amount, or as a percentage of the price the retailer paid.

​Markdown

​How much a retailer decreases the price over what they originally had it priced for. Shown as an amount, or as a percentage of the price the original.

​Commissions

​A fee paid for services, usually a percentage of the total cost.

​Tip/Gratuities

​A tip or gratuity is an amount of money that is given to a worker such as a waiter or waitress who performs a service for you. A common tip amount is 15% of the cost of the meal or other service. Generally a tip is determined based on the total bill which includes the cost of the meal and sales tax.

​Interest

​interest is a fee paid for borrowing money or other assets

.• the amount borrowed is called the principal

.•  the interest is expressed as a percentage rate of the principal for a given time interval.

​Scale Factor

The ratio of the length of any object on a model (blueprint) to the actual length of the same object in the real world.

Formulas​

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​Percent Change

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​Percent Error

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​Scale Factor

​where r is the radius of the circle

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diameter = radius x 2

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where d is the diameter of the circle​

where b is the base and h is the height​

area of a rectangle = length x width​

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Volume of a rectangular prism = length x width x height​

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