What is an odd number multiplied by an odd number?

Answer 1

A definition of an odd number is 2n-1 where n is any integer. The product of two

odd numbers is thus (2n-1)(2p-1) for any numbers n and p. Expanding the expression

yields 2(2pn -(p+n)) + 1. The term on the left is even by definition. Adding 1 to any even number is, by definition, an odd number. Therefore, the conclusion is elementary (Watson); the product of two two odd numbers is an odd number