Read Basic Math and Pre-Algebra For Dummies Online
Authors: Mark Zegarelli
Every mixed number has both a whole number part and a fractional part. So the three numbers in a mixed number are
For example, in the mixed number
, the whole number part is 3 and the fractional part is
. So this mixed number is made up of three numbers: the whole number (3), the numerator (1), and the denominator (2). Knowing these three parts of a mixed number is helpful for converting back and forth between mixed numbers and improper fractions.
To convert a mixed number to an improper fraction, follow these steps:
For example, suppose you want to convert the mixed number
to an improper fraction. First, multiply 3 by 5 and add 2:
Place this result over the denominator:
So the mixed number
equals the improper fraction
. This method works for all mixed numbers. Furthermore, if you start with the fractional part reduced, the answer is also reduced (see the earlier “Increasing and Reducing Terms of Fractions” section).
To convert an improper fraction to a mixed number, divide the numerator by the denominator (see Chapter
3
). Then write the mixed number in this way:
For example, suppose you want to write the improper fraction
as a mixed number. First, divide 19 by 5:
Then write the mixed number as follows:
This method works for all improper fractions. And as is true of conversions in the other direction, if you start with a reduced fraction, you don't have to reduce your answer (see “Increasing and Reducing Terms of Fractions”).
Cross-multiplication is a handy little technique to know. You can use it in a few different ways, so I explain it here and then show you an immediate application.
To cross-multiply two fractions, follow these steps:
For example, suppose you have these two fractions:
When you cross-multiply, you get these two numbers: