Determining whether a number is even or odd is a fundamental mathematical skill. An even number is an integer that is divisible by two without leaving a remainder. For example, -4, 0, 8, 123456 are all even numbers, whereas -3, 5, 7, 21 are odd numbers.
Checking if a number is even has practical applications in various fields, including computer science, statistics, and physics. In computer science, for instance, even numbers are often used to represent binary digits (bits), the fundamental unit of data storage. In statistics, even numbers are used to identify even-numbered pages in a book or data set.