Operations with Fractions/ Decimals

By: Gracie

Adding and Subtracting Fractions w/ Different Denominators

Step 1: Look at your fraction. If it is a mixed number, change it into an improper fraction.


Step 2: Find the greatest common multiple. You do that by listing all the multiples of BOTH denominators.

Step 3: Multiply the numerator. If you multiplied the denominator by 4, you would also multiply the numerator by 4. Do that with both fractions.


Step 4: Add or subtract. You add or subtract the numerator, depending on the operation. You do NOT add or subtract the denominator.


Step 5: If it is improper, change it into a mixed number. If it is not in its simplest form, simplify it.

Video For Adding and Subtracting w/ Different Denominators

Adding and Subtracting Fractions w/ the Same Denominators

Step 1: Look at your fractions. If it is a mixed number, change it into an improper fraction.


Step 2: Add the numerators.


Step 3: If it is improper, change it into a mixed number. If it is not in its simplest form, simplify it.

Video for Adding and Subtracting w/ the Same Denominator

Multiplying Fractions

Step 1: Look at your fractions.


Step 2: Multiply the numerator by the other fraction's numerator.


Step 3: Multiply the denominator by the other fraction's denominator.


Step 4: If the fraction is not in its simplest form or it is an improper fraction, you need to simplify to its simplest form or convert it into a mixed number.

Video for Multiplying Fractions

Dividing Fractions

Step 1: Look at your fraction. If it is a mixed number, you need to change in into an improper fraction.


Step 2: Keep the first fraction. You CANNOT keep the other fraction. You will get the incorrect answer.


Step 3: Change the division sign to a multiplication sign.


Step 4: Flip the numerator to the denominator's place, and the denominator to the numerator's place.


Step 5: Even though it's division, you need to multiply like in a multiplication problem with fractions.


Step 6: If the fraction is not in its simplest form or is an improper fraction, simplify it or change it into an improper fraction.

For Extra Help...

For extra help, here is 2 videos on how to convert fractions into mixed numbers and convert fractions into an improper fraction.


Converting improper fractions to mixed numbers: http://youtu.be/vVa19AHM0Zc


Converting mixed numbers into improper fractions: http://youtu.be/shpf9krdXQQ

Adding With Decimals

Step 1: Write out your problem like a normal addition problem.

Step 2 (OPTIONAL): Get rid of all the zeros at the very end of a decimal. Not if it was in the middle of a decimal, only the last digit.

Step 3: Bring your decimal down, right below where it was before.

Step 4: Add! Every number before the decimal, put before the decimal. Anything after the decimal, put after the decimal.

Step 5: If the last digit of the sum has a 0, you can get rid of the 0.

Adding Decimals Example

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Adding With Decimals Example 2

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Subtracting With Decimals

Step 1: Write out your subtraction problems like a normal subtraction problem.

Step 2: Add a place holder if you need to.

Step 3: Bring your decimal straight down.

Step 4: Subtract like a normal subtraction problem. Any numbers before the decimal still go before the decimal, and any number after the decimal goes after the number.

Step 5: Get rid of any 0's at the very END of your number, not in the middle.

Example for Subtracting with Decimals

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Video for Adding and Subtracting with Decimals

Decimal Operations, Baby! (Addition & Subtraction) Full Song

How to Multiply Decimals

Step 1: Write your multiplication problem normally, and get rid of any 0's at he end of either decimal.

Step 2: Multiply like a normal multiplication problem.

Step 3: Count how many digits there are after the decimal on BOTH decimals. That's how many digits you'll move your decimal over from the righthand side. If there is any space between one place value, add a 0.

Step 4: Get rid of any extra 0's in the product.

Example for Multiplying Decimals

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Video for Multiplying Decimals

Multiplying Decimals

How to Divide Decimals

Step 1: Write out your problem as a normal long division problem.

Step 2: You canNOT have you divisor a decimal, so you will push the decimal over 1 spot in the divisor AND dividend.

Step 3: Bring your decimal right above where it was.

Step 4: Do normal long division. If the number after the decimal in the dividend, put the number up after the decimal in the quotient. Same the other way around.

Step 5: Get rid of the very last 0 if you have one.

Example of Dividing Decimals

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Video On Dividing Decimals

How To Divide Decimals