09

09 is a two-character token consisting of the digits 0 and 9. In decimal notation, it represents the integer 9, with leading zeros often used to produce fixed-width formatting.

In mathematics, 9 is a perfect square (3^2) and a composite odd number; its divisors are 1, 3, and 9. The presence of a leading zero does not change its mathematical value in standard arithmetic.

In computing, leading zeros indicate fixed-width fields or padding. However, depending on the programming language, a leading zero may denote octal notation, which can make a code like 09 invalid in languages that treat numbers with a leading zero as octal literals.

In calendars and time notation, 09 commonly refers to September, the ninth month in many month-numbering schemes, or to nine o’clock in 24-hour time (09:00). In date formats that separate year and month, 09 may appear as the two-digit representation of September.

In other contexts, 09 is used in product codes, version numbers, or identifiers where a two-digit suffix is meaningful. It can also denote the year 2009 when used as shorthand or within chronological labeling. Overall, 09 is primarily a formatting and representation choice that maps to the underlying value 9 in most contexts.