Programmer's Day, also known as the Day of the Programmer, is a professional day that is celebrated in Russia on the 256th (hexadecimal 100th, or the 28th) day of each year (September 13 during common years and on September 12 in leap years). The number 256 (28) was chosen because it is the number of distinct values that can be represented with a byte, a value well known to programmers. 256 is als