Instructables

Multiplying Fractions

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So you need to know how to multiply with fractions, huh? Well look no further than this Instructable! Here you can see how to multiply not only fractions, but also mixed numbers! Here goes nothing!
 
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Step 1: Make it a Fraction ( For Mixed Numbers Only )

Picture of Make it a Fraction ( For Mixed Numbers Only )
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So, what is a mixed number? It is simply a number that has a whole part, and a part of a whole, such as one and one seventh, three and three fourths, etc. Also you should know that the numerator is the top number in a fraction, and the denominator is the bottom one. To convert the mixed number into a fraction, multiply the whole number by the denominator, then add this number to the numerator. This is your new numerator, and your denominator stays the same.

As an example, we'll use three fourths times one and one seventh. ( 3/4 ) * ( 1 1/7 )

Step 2: Cross-Reducing

Picture of Cross-Reducing
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This part will make your life much easier. Now, you should cross-reduce. To cross-reduce, you must rewrite the two fractions like picture 1. Then you draw imaginary lines diagonally and if either of the two sets of numbers have a common factor over one, you can divide both of them by the greatest factor. To find the greatest common factor, or GCF, you can either use your own way, or make factor rainbows, like picture 3. Make sure you have the GREATEST common factor, or else you will have to divide again. Now for the multiplication.

For our problem, the four and the eight have common factors, and the greatest common factor is four.
MROHM3 years ago
VERY HELPFUL COLUMN !!!! MANY THANKS!!!