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Adding Decimals


The process of adding decimals is very similar to adding whole numbers. Doing so is simple if you remember to pay attention to the position of the decimal point when adding.


Decimal Point - The decimal point looks like a period and is always placed after the “ones” position of a number.
Decimal Notation - Decimal notation is useful for writing numbers which are not whole numbers.
Whole Number - A whole number is a number with nothing but zeroes after the decimal point (5.0) or with no decimal point at all (5).


The most important thing to remember about adding decimals is to make sure that the decimal place lines up when adding. .1+.01=.11.1+.01=.11, for example. To make things easier, it may be helpful to place additional zeroes after the shorter number until both numbers have the same amount of digits.

For example, when adding .05 and .0034, the addition is more straightforward if you write the equation as .0500+.0034=.0534.0500+.0034=.0534. Lining it up vertically makes it easier to solve:

+ .0034


Adding Decimals (Example 1)

0.234+0.3450.234 + 0.345
Add the digits in the Thousandths column (4+5 = 9)
Add the digits in the Hundredths column (3+4 = 7)
Add the digits in the Tenths column (2+3 = 5)
Add the digits in the Ones column (0+0 = 0)

Adding Decimals Worksheets (PDF)

Adding Decimals Worksheet 1

Adding Decimals Worksheet 2

Adding Decimals Worksheet 3