Multiplying
Multiplying fractions is quite easy if you follow these steps.
Simply multiply the numerators (top numbers) and multiply the denominators (bottom numbers) and then simplify if needed.
Examples:
- 2/3 x 4/5 = 8/15
(No simplification required as no whole number divides evenly into 8 and 15.)
- 5/8 x 3/5 = 15/40 (divide both numerator & denominator by 5) = 3/8
Dividing
To divide fractions, you will need to change things around a bit. Once the changes are made, however, you can simply follow the multiplication rules.
For division, use the reciprocal of the fraction being divided (basically flip it!).
Examples:
- 3/ 4 ÷ 1/ 4
= 3/ 4 x 4/1
= 12/4 (then simplify by converting to a whole number)
= 3
- 5/6 ÷ 4/5
= 5/6 x 5/4
= 25/24 (then simplify by converting into a mixed number)
= 1 1/24
Whole and Mixed Numbers
Sometimes you will have mixed number or whole numbers as well as fractions. Not to worry, the methods here are just as easy.
Turning whole numbers into fractions is simple – simply put the number over 1.
For example: 5 becomes 5/1 or 137 becomes 137/1
Example:
- 5/8 x 6
= 5/8 x 6/1
= 30/8 (simplify) = 3 6/8 = 3 3/ 4
Mixed numbers need to be converted into improper fractions. To do this multiply the denominator by the whole number and add the numerator.
Example: 2 7/9 = 25/9
Let’s try a couple of examples for multiplying mixed numbers.
Examples:
- 4 ¾ x 5
= 19/4 x 5/1
= 95/4
= 23 ¾
- 3 2/3 x 4 1/6
= 11/3 x 25/6
= 275/18
= 15 5/18
Now for a couple division questions.
- 4 3/8 ÷ 2 1/ 2
= 35/8 ÷ 5/2
= 35/8 x 2/5
= 70/40
= 1 30/40
= 1 ¾
- 6 1/ 2 ÷ 2 1/3
= 13/2 ÷ 7/3
= 13/2 x 3/7
= 39/14
= 2 11/14
As you can see, multiplying and dividing fractions is not all that scary as long as you follow the steps.
I do realize that some of you might not be familiar with a few of the steps that come before in fractions. If you would like a nice introduction to fractions or a reminder, I do have a course that covers all the basics of fractions.
(If the sale price has lapsed, send me an e-mail, and I can provide you with a coupon.)
The Complete Fractions Course
In the meantime, have fun with fractions!