A numerical digit is a symbol used to represent numbers in mathematics. The most common numerical digits are the ten symbols from 0 to 9, which are used in the decimal system. Each digit has a specific value based on its position in a number, allowing for the representation of larger quantities. In addition to the decimal system, there are other numeral systems that use different digits, such as binary (which uses only 0 and 1) and hexadecimal (which includes digits from 0 to 9 and letters A to F). These systems are essential in various fields, including computer science and digital electronics.