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Adding and Subtracting Decimals

So you have a couple of decimals that you need to add or subtract? Good news! As long as you can add and subtract whole numbers, you know how to do it with decimals, too.
Let's go ahead and look at how to do one:
Solve: 3.145 + 2.174

We generally find it easier to write the problem vertically (that's "up and down"), so let's do that first:


To solve this problem, in your answer, drop the decimal point down exactly where it appears in the number, then add. You should get:


We won't go any further into the process of adding the numbers, but the most important thing to remember when using decimals when adding and subtracting is to keep the decimal point in it's proper position. All the decimal points should be in the same position for each number. Here are some examples:

Correct:
Incorrect:



Note: If it helps to visual the problem, you can add 0's after the last digit of a decimal. If you did it to the problem above, you would get:


Subtraction
Since the *only* different between subtracting and adding decimals is the part where where you actually add or subtract (everything with the decimals themselves stays the same), there is not much else to say here. Review the addition steps (above) but replace the +'s with -'s!

Once you've mastered that, it's time to move onto Multiplying and Dividing Decimals.

Find another math lesson at the Math Lesson and Tutorial Center!


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