The chapter deals with rational numbers, the representation of rational numbers on the number line, and also finding a rational number between two numbers. Further, the properties of rational numbers such as closure, commutativity, associativity, and reciprocal of rational numbers are explained in Math chapter 1 Rational number.
A number is called rational if it can be expressed in the form p/q where p and q are integers and q > 0. Thus, it has all-natural numbers, whole numbers, and integers. It is also a part of real numbers. Any fractional number with non-zero denominators is called a Rational number. So, we can say zero '0' is also a rational number, as we can say it as 0/1, 0/2, 0/3, 0/4, 0/4, etc. At the same time, 1/0, 2/0, 3/0, 4/0, 5/0, etc., are not rational numbers because they do not have finite values.
The RD Sharma Maths chapter 1 Rational numbers cover additive inverse of rational number, associativity of rational numbers, closure property of rational numbers, commutative property of rational numbers, concepts of rational numbers, distributivity of multiplication over addition for rational, the identity of addition and multiplication, negative of a number, the role of zero, the role of 1. 0 is the additive identity, and 1 is the multiplicative identity for rational numbers. Between any two rational numbers, there lie infinite rational numbers. The commutative and associative property applies for whole numbers and natural numbers and multiplication but not subtraction and division.