Fourdigit

Fourdigit is a term used to describe entities that consist of exactly four decimal digits. As a mathematical concept, a four-digit number is any integer from 1000 to 9999, inclusive. Such numbers have a fixed width in base-10 representation and are typically used in counting, labeling, and sequencing tasks.

In computing and information security, four-digit codes are common for authentication and access control. Four-digit Personal Identification Numbers (PINs) are widely used for bank cards, devices, and some software services. While convenient and easy to remember, four-digit codes offer limited entropy compared with longer passwords, making them more susceptible to guessing or brute-force attempts if proper protections such as rate limiting and account lockouts are not in place.

Four-digit formatting also appears in data representation. When fixed-width fields are required, smaller numbers are often zero-padded to four digits, producing strings like "0007" or "0123" rather than compact numeric values. This distinction between numeric value and string representation is important in databases, programming, and data interchange.

Related topics include the general concept of digits, fixed-width numeric fields, and the use of four-digit codes in calendars and identifiers. While “fourdigit” does not denote a single, universally defined object, it commonly refers to the class of four-digit numbers or four-character codes across mathematics, computing, and data formatting.