How to Add and Multiply Decimals

Step-by-Step Guide

1. 1

   Step 1: Write the numbers with the decimals aligned vertically.

   The numbers should be stacked on top of each other.
   
   This ensures that the place values are lined up, so that you add your digits correctly.
   
   The numbers will not necessarily be right-aligned at this point, as they usually are when adding numbers.
   
   For example, you might need to add the numbers
   15.525 and
   7.92.
   
   If you align your decimal points, the 2s in the hundredths place of both numbers should be aligned vertically, as should the digits in the tenths and ones place.
2. 2

   Step 2: Make the numbers the same length.

   This means the numbers should have the same number of digits.
   
   Add zeros to the end of the numbers to make them right-aligned.Make sure that the place values of each number line up.
   
   For example, you should add a 0 to the thousandths place of
   7.92, changing the number to
   7.920.
   
   The two numbers should now be right-aligned. , Begin with the place value farthest to the right.Add the digits together, carrying into the next place value if necessary.
   
   Ignore the decimal point for now, and add the digits as normal.
   
   For example, adding, 15525 and 7920, you should end up with
   23445. , The decimal point in your answer should be aligned with the decimal points in your two addends.
   
   For example,
   15.525+7.92=23.445{\displaystyle
   15.525+7.92=23.445}.
3. 3

   Step 3: Add according to the standard algorithm.

4. 4

   Step 4: Drop the decimal into your sum.

Detailed Guide

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