Guides
Worked explanations for the everyday math that shows up in shopping, business, and school. Each guide walks through the concept step by step and links to the calculator that handles the arithmetic for you.
Percentages
How to calculate percentages
The three core operations, the "of means multiply" trick, and mental-math shortcuts for 10%, 15%, and more.
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Business math
Markup vs margin explained
Why a 50% markup is only a 33% margin — the single most-confused distinction in everyday business arithmetic.
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Smart shopping
How to find the best unit price
Price ÷ size = unit price. Why the bigger package isn't always cheaper, and how to compare items measured in different units.
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