Lesson · M.1.6
Percentage problems
How to turn a percentage into a decimal and use it to find a discount, a tax, a tip, or a raise, with a worked example for each direction.
ObjectiveM.1.6Read2 minExam weightNumbers and Algebra ≈ 53% of Mathematics
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See editions and pricing →What you will be able to do
- Convert a percentage to a decimal before performing any calculation.
- Calculate a percentage increase or decrease in a single multiplication step.
- Identify wording that signals an increase versus a decrease.
What the lesson concludes
- Convert the percentage to a decimal before multiplying: divide by 100.
- To find a percentage of a quantity, multiply the quantity by the decimal.
- For an increase, use 100% plus the rate; for a decrease, use 100% minus the rate, then multiply once.
- Tax, mark up, commission, and raises increase the base; discounts, mark downs, and depreciation decrease it.
- Cross-check an increase or decrease with the two-step method if you have time to spare.