Students regularly make unnecessary mistakes with decimal places on the exam. Although you probably learned decimals some time ago, make sure you know the tips or procedures to divide and multiply decimals outlined in this lesson. The rules will help you avoid mistakes and make decimal calculations more quickly.

TIPS: (see PDF worksheet for examples)

1. Addition: – line up addition and subtraction calculations vertically.
2. Multiplication – convert every decimal to a whole number and multiply. Add the number of digit places to the right of the decimal points for every number included in the product. Add back that total number of decimal places to the integer result.
3. Division – Move the decimal places in the denominator to make it a whole number. Move the decimal places in the numerator by the same amount and then divide integers.
4. Complex – Convert each decimal to an integer number multiplied by a power of 10. Make the appropriate calculations on the integers and the powers of 10 separately (easier to simplify and compute). Convert the result back into a decimal format.