5. Complex fractions
6. Reciprocals.
Improper fractions have numerators that are larger than or equal to their denominators.
Examples:
are
improper fractions.
Mixed numbers have a whole number part and a fraction part.
Examples:
are mixed
numbers also written as
. Here we denote
mixed numbers in the form
.
3.1 Converting Mixed Numbers to Improper Fractions
To change a mixed number into an improper fraction, multiply the whole number by the denominator and add it to the numerator of the fractional part.
Examples:
3.2 Converting Improper Fractions to Mixed Numbers
To change an improper fraction into a mixed number, divide the numerator by the denominator. The remainder is the numerator of the fractional part.
Examples:
= 11 ÷ 4 = 2 r3 = 2 3/4
= 13 ÷ 2 = 6 r1 = 6 1/2
Equivalent fractions are different fractions which name the same amount.
Examples:
The fractions
are
all equivalent fractions.
The fractions are
all equivalent fractions.
We can check if two fractions are equivalent by cross-multiplying their
numerators and denominators. This is also called taking the cross-product.
Example:
Check if
are
equivalent fractions.
The first cross-product is the product of the first numerator and the second
denominator: 3 × 42 = 126.
The second cross-product is the product of the second numerator and the first denominator: 18 × 7 = 126.
Since the cross-products are the same, the fractions are equivalent.
Example:
Check if
are
equivalent fractions.
The first cross-product is the product of the first numerator and the second
denominator: 2 × 20 = 40.
The second cross-product is the product of the second numerator and the first denominator: 4 × 13 = 52.
Since the cross-products are different, the fractions are not equivalent
5. Complex fractions
A complex
fraction (or compound fraction) is a fraction in which the numerator and
denominator contain a fraction. For example, ½⁄⅓ is a
complex fraction. To simplify a complex fraction, divide the numerator by the
denominator, as with any other fraction: ½⁄⅓ = 3⁄2.
6. Reciprocals.
The reciprocal of a fraction is obtained by switching its numerator and denominator.
To find the reciprocal of a mixed number, first convert the mixed number to an improper fraction, then switch the numerator and denominator of the improper fraction.
Notice that when you multiply a fraction and its reciprocal, the product is always 1.
Example:
Find the reciprocal of
We switch the numerator and
denominator to find the reciprocal:
.
Example:
Find the reciprocal of
First, convert the mixed number to an improper fraction:
=
Next, we switch the numerator and denominator to find the reciprocal: