Graduate Management Admission Test (GMAT) Practice Test

What is the product of an odd number and an odd number?

1. Even

2. Odd

3. Undefined

4. Both Even and Odd

The correct answer is: Odd

When multiplying two odd numbers, the result is always odd. This can be understood through a basic understanding of how odd and even numbers interact with each other. An odd number can be expressed in the form of 2n + 1, where n is an integer. When you multiply two odd numbers, say (2n + 1) and (2m + 1), you can use the distributive property: (2n + 1)(2m + 1) = 4nm + 2n + 2m + 1. In this expression, 4nm + 2n + 2m is clearly an even number because it can be factored as 2(2nm + n + m). When an even number is added to the odd number 1, the result remains odd. Thus, the product of any two odd numbers will always yield an odd number. Understanding this property of multiplication with odd integers solidifies why the correct answer is indeed odd.