# Introduction

If you count your fingers and toes, you will come to 20 (most of you will), and that is a natural number. The integers form the basic number set. These are counting numbers, both positive and negative.

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Ratios of integers are called rational numbers, and you get one for any pair of integers, so long as the second integer, called the denominator, is not zero. Ratios like which are not themselves integers are called fractions. There is one thing we cannot do with our rational numbers, and that is to divide by 0.

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The number of the form, where

*p*and

*q*are integers and

*q*Â¹0 is called a rational number.Â

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**Example :Â **Â are all rational numbers.

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Fractions asÂ Rational Numbers :-

A fraction is in the form* * whereÂ *p*Â andÂ *q*Â are positive integers andÂ *q*Â Â¹Â 0. Therefore every fraction is a rational number.Â

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Integers as Rational Numbers :-

The integer 7 can be written asÂ .

The integer -7 can be written asÂ .Â

Therefore, all integers can be written in the form

whereÂ *q*Â = 1. All integers are therefore rational numbers.