Programmers' Day (Russian: День программи́ста) is an official professional holiday in Russia, celebrated on the 256th (0x100th) day of each year (September 13 during common years and on September 12 on leap years).
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The number 256 (28) was chosen because it is the number of distinct values that can be represented with an eight-bit byte—a number that is typically very well known to programmers.[7] Starting from zero, the 256th value represented by a sequential permutation of 8 bits is unsigned integer 255 or hexadecimal 0xff or binary 0b11111111. 256 is the highest power of two that is less than 365, the number of days in a common year.
