Lesson 4
Adding and Subtracting Decimals

The procedures for adding and subtracting decimals is nearly the same as for adding and subtracting whole numbers. The only difference is that you must align the decimal points in order to make sure you are adding the same place values—ones to ones, tenths to tenths, hundreds to hundreds, hundredths to hundredths, and so on.

Step 1: Write the decimal values in vertical form, aligning the decimal points.

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Note: Aligning the decimal points automatically aligns the place values—ones with ones, tenths with tenths, and hundredths with hundredths.

Step 2: Add  or subtract the values in the same way you would add or subtract any column of numbers, placing the decimal point directly in line with the decimal points in the addends.

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Add or subtract these decimal value as indicated.


Go to these tutorials if you find you are having trouble the adding or subtracting decimal values.