Number representation refers to the way numbers are expressed in different systems, such as the decimal system, binary system, or hexadecimal system. The decimal system, which uses ten digits (0-9), is the most common in everyday life. In contrast, the binary system, used in computers, relies on just two digits (0 and 1) to represent all values. Different number representations are essential for various applications. For example, binary is crucial for digital electronics and computing, while hexadecimal is often used in programming to simplify binary code. Understanding these systems helps in fields like mathematics, computer science, and engineering.