Common fractions describe rational numbers as
ratios of one integer divided
by another integer. The top or first part of a common fraction is the
numerator, and the bottom or second part of the fraction is
the denominator. The denominator cannot
be zero because a number divided by zero is undefined
or infinity. The reciprocal
of a fraction is the number created by switching the numerator and the
denominator. If the number is a whole integer, then the reciprocal is
one over the integer. Reduce a common fraction when possible by dividing
down the numerator and the denominator with any common integer divisors.
A fraction in proper form also has a numerator smaller than the denominator.
If the absolute value of the numerator is greater
than the absolute value of the denominator, then convert the fraction
to an integer combined with a common fraction in proper form. Conversion
to the proper form is done by dividing the numerator by the denominator.
Since a common fraction is a rational number it can also be expressed
as a decimal fraction. A common fraction cannot
represent an irrational number, because irrational
numbers cannot be expressed as one number divided another number.