Revision sheet

All the summary cards of the chapter on one page. Print it, or save it as a PDF from the print window.

Defining quantities

Name each quantity with its unit and period; compare with rates.

Watch out: a vague variable ("x = money") leads to a wrong model.

Converting units

To a smaller unit: multiply; to a larger unit: divide.

Watch out: check that the answer makes sense in size.

Percent error

Error ÷ actual × 100.

Watch out: divide by the actual value, not the measured one.

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