Explanation:
Rational number
In mathematics, a rational number is any number that can be expressed as the quotient or fraction a/b of two integers, with the denominator b not equal to zero. Since b may be equal to 1, every
integer is a rational number. The set of all rational numbers is
usually denoted by a boldface Q
The decimal expansion of a rational number
always either terminates after finitely many digits or begins to repeat the same finite sequence of digits over and
over. Moreover, any repeating or terminating decimal represents a rational
number. (Our solved example in mathguru.com uses this concept).
These
statements hold true not just for base 10, but also for binary, hexadecimal, or any other
integer base.
The term rational in reference to the set Q refers to the fact that a
rational number represents a ratio of two integers. In mathematics, the adjective rational often means that the underlying
field considered is the field Q of rational numbers.
http://en.wikipedia.org/wiki/Rational_number
In mathematics, an irrational number is any real number which cannot be
expressed as a fraction a/b, where a and b are integers, with b non-zero, and is
therefore not a rational number. Informally, this means that an irrational number cannot be represented as
a simple fraction. Irrational numbers
are precisely those real numbers that cannot be represented as terminating or repeating decimals. (Our solved example in
mathguru.com uses this concept).
The best-known irrational
numbers are π, e and √2.
http://en.wikipedia.org/wiki/Irrational_number
The above explanation is copied from
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