Karessa's Last Fraction Post

Monday, May 11, 2009
Adding and Subtracting Fractions
Adding fractions can be confusing if you don't understand it. But, it can actually be quite simple if you do understand it. An example of adding fractions is 5/7 + 1/2:

To add fractions, you find the common denominator. Then, to find out the numerator, you cross multriply (it's the easiest way)

Another example of adding fractions is 5/9 + 1/3.

One last example on adding fractions is 10 1/2 + 6 4/5.

For subtracting, I'll use 3 3/8 - 2 3/4 as an example.

Subtracting fractions is basically the same as adding them; the rules still apply. But when you have a mixed number, you change it into an improper and subtract from there.
* To convert a mixed number into improper, multiply the whole number by the denominator and add the numerator.

Multiplying Fractions

Multiplying fractions is pretty straight forward; just multiply the numerators together and the denominators together. Simplify if possible. An Example is 4/5 x 1/2.

The next example contains a mixed number. All you have to do is convert the mixed number into an improper fraction, multiply, and then convert it back into a mixed number as your answer.

Dividing Fractions
Ask yourself the question "How many groups of __ are in __?" when dividing fractions. I'll explain how to divide fractions by using a ration table.
Example: 3/4 / 1/3.

Word Problems

Fifteen scoops of flour makes 6 2/3 cakes.

This question is pretty self-explanatory; all you have to do is multiply how many hours of daylight by the period of how long it was sunny.


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