Rational numbers

Rational numbers are those numbers that are of the form of p / q, where q is not equal to zero.
For example, all integers are rational numbers because every integer can be written in the form of p / q as follows:
1 = 
-1 = 
100 = 
More rational numbers are 2/3, 4/5, 6/7, which are not integers but they are rational because they are in the form of p/q.

Non recurring and non terminating decimals are not rational numbers. These are those decimals, that keep on getting more digits after the decimal point, and they show no repetition of a single or a set of digits after the decimal point. For example, square root of 2 is not a rational number because it results in a decimal number that keeps going on without showing any repetition in digits.

Similarly √3, √5, √6, √7 .. are not rational numbers. Square roots of perfect squares, and some other square roots which result in a terminating decimal are rational numbers. For example √100 and √9 are rational numbers, and so are √1.21, √2.25 and √1.69.

Zero is a rational number, because zero divided by 1 is 0, and 0/1 is in the form of p/q.

All those numbers which have a zero in their denominator, for example, 1/0, 100/0, -1/0 are not rational numbers because dividing by zero does not give a definite result.