Adding/ Subtracting Decimals

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1) Re-write the expression vertically. Just like when adding whole numbers, you need to line up the digits by place value.

2) Use the decimal point to help you line up the place values. The decimal point for each number being added/subtracted must be in the same location for each number.

3) If there are any “missing digits” use a zero to hold the place value.

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 23.5        23.50

+ 2.52     + 2.52

                   26.02

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Multiplying Decimals

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You do NOT need to align the place values to multiply decimals. In fact, doing so will force you to do extra work!!!

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1) Write each number all the way to the right. 2) Multiply using the standard algorithm. - remember to bring down the zeros

3) Count the number of digits that are to the right of the decimal point in the problem.

4) Starting at the far right hand side of your product count in the number of digits you counted in step four and place your decimal point there.

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Example

 9.65         9.65           = 5.790

x 0.6        x 0.6

                    5790

               0000

                    5790

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Dividing Decimals

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1) If the divisor is not a whole number, move the decimal point to the right to make it a whole number

2) Move the decimal point in the dividend the same number of places you moved it in the divisor

3) Divide as you would normally divide.

4) Put decimal point directly above decimal point in the dividend.

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Example

43.16 ÷ 8.3          8.3  43.16        

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                 xx5.2

            83 43 1.6

                -415

                   166 

                   166

                      0