Operations with Fractions/Decimals

By: Ann V

Adding and Subtracting

Explanation

Step1: When you are adding or subtracting fractions with different denominators, find a common denominator. Now how do you do that? It's actually very simple. All you need to do is find the least common multiple of the two denominators of those fractions. If you forgot what a multiple is, that's okay!! A multiple is the result in multiplying a number by another number.


Step 2: Once you find a common denominator, see how many multiples it took to get there. Multiply that number for both your numerator and denominator.


Step 3: After you have found the common denominators, look at your equation to see if you should either add or subtract the two fractions. If you can simply your answer once your done (make it any smaller) do so!

Example

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Click here to watch a video on adding fractions with different denominators.

Multiplying

Explanation

Step 1: When you are multiplying fractions, multiply the numerator and denominators of your fractions.


Step 2: Once you get your product, you might think your done; but if you can simplify your product, do so! Simplify means to simply reduce your answer.

Example

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Dividing

Explanation

Step 1: Your first step in a division problem is to find the reciprocal of your second fraction. Reciprocal is just a fancy way to say you flip the numerator and denominator of that fraction to get a new fraction.


Step 2: Rewrite your division problem into multiplication form. Write your original fraction first times your reciprocal of your second fraction.


Step 3: Multiply your two fractions to get your product; but your not done yet! If you can simplify your product, do so! Simplify just means to simply reduce your answer.

Example

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Multiplying Decimals

Explanation

Step 1: Line your decimals up.


Step 2: Act like the decimals aren't there, and do your regular U.S. algorithm by multiplying.


Step 3: When you get your product, keep the decimals back. Count the total decimal places and put that many places in the product.

Example

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Dividing Decimals

Explanation

Step 1: Rewrite your division as a fraction.


Step 2: Multiply your numerator and denominator by the power of ten to make your divisor a whole number.


Step 3: Divide your new dividend and divisor. Once you find the product, count the total decimal places and put that many places back in you product.

Example

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