ParaPro Math Study Guide: Decimals

Numbers that are written with decimals refer to a system of numbers based on the powers of 10.

To add or subtract decimal numbers, you line up the decimals vertically and add/subtract.  You would use 0’s where there are any missing digits.  The decimal point stays in the same location throughout.

To multiply decimals, you line up numbers from the right, perform multiplication, and put back into your product however many digits after the original decimals in total.

To divide decimals, you can perform long division.  If it is easier, you can move the decimal in both what you are dividing by (divisor) and in what you are dividing into (dividend).  It is often easier to divide decimal numbers if you are able to convert the divisor into a whole number. 

To compare the values of decimals, you can write all values with the decimals lined up.  It is now easier to compare the values of the decimals because you can easily compare one place value at a time.

To convert a decimal to a fraction, you can put the decimal number over its place value.  If necessary, simplify the resulting fraction.

Example A

Add $.523+2.104$

Example B

Subtract $3.451-2.94201$

Example C

Multiply $(2.941)(3.51)$

Example D

Divide $13.2174÷2.1$

$13.2174÷2.1$ is equivalent to $132.174÷21$

Decimals Review Test

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