5.2+Adding+and+Subtracting+Decimals

Section 5.2 - Adding and Subtracting Decimals
When you line whole numbers up to add or subtract, you line them up by the ones digit (on the right) so that the numbers are in the same place value. Then, when you add within columns, the numbers stay in place value (except for borrowing or carrying) and the answer is correct.

The decimal point is a place marker -- it marks the spot between the ones place and the tenths place, or between whole numbers and fractions. That means that if you line two numbers up by their decimal points, regardless of how many digits the number have on the right or left of the decimal point, they will still match up by place value. You will see that the "ones" column still lines up, as do all the other place value columns. The decimal point is placed in the answer directly below where it is in the numbers being added or subtracted.



Sometimes, however, there aren't the same number of digits in the two decimal numbers to be added or subtracted. You can add multiple zeroes to the end of a decimal number without changing the value of the number. This might help in adding or subtracting columns.



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 * What about with variables?**

No difference with the rules -- you can't add unlike terms!

3.409W + 0.23 = 3.409W + 0.23 (can't add variables and numbers)


 * Chapter Five Practice Problems**

**Where to from here?**
5.1 Decimals and Fractions 5.2 Adding and Subtracting Decimals 5.3 Multiplying Decimals 5.4 Dividing Decimals 5.5 Application Problems with Decimals Chapter Five Summary Chapter Five Homework