Decimals – I Need Help Adding Decimals

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     They key to adding decimals is to line up the decimal points and places!

     Students must first have a thorough understanding of decimal place value (i.e. tenths, hundredths, thousandths, etc). 

     When adding decimals, students must remember to:

·         Line up the decimal points in the exact same position, one right below the other.

·         Make sure to line up the decimal place (i.e. the tenths digit in one decimal number with the tenths digit in the other decimal number and the hundredths, thousandths, etc).
 

1)  For example, let’s add 0.24 and 0.37.  The first thing we must do is line up the decimal points.

    0.24

+  0.37     Notice how the decimal points are in the exact same position.

       1

    0.24

+  0.37     Then, we simply add.

    0.61

2)  When adding decimals, students often get confused when adding decimals and whole numbers.  For example, let’s add 3.02 and 0.83.

    3.02

+  0.83     Notice how the decimal points are lined up again!  Quite often, students line up

                 the zeros. 

    3.02

+  0.83     Again, we simply add the decimals, making sure the decimal is in the correct

    3.85     place in the answer.

3)  Finally, sometimes decimal numbers do not appear to be the same length.  For example, in problem 4.71 + 0.3, we notice that in the first number, we have 3 digits and in the second number, we have 2 digits.  When we add them, they should look like this:

   4.71

+ 0.3        This may look incorrect, but it isn’t.  We perfectly lined up the decimals!

   1

   4.71

+ 0.3        Again, we simply add, making sure the decimal is lined up in the answer.

   5.01

     Regardless of the number of digits in the decimal number, it is important that students remember to line up the decimals in the question and answer when adding decimals.

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 Learn'Em Good - Fractions and Decimals - by Stuart Ackerman MSc.Ed.,B.A.

Easy to Use Lessons and Worksheets to Help Improve Your Grade 1-8 Child's Fraction and Decimal Skills