Happy Programmers’ Day, colleagues!
Programmers’ Day is an international unofficial professional holiday that is also officially recognized in Russia, celebrated on the 256th (0×100th) day of each year (September 13 during common years and on September 12 in leap years)
The number 256 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. 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.
by Wikipedia [en.wikipedia.org]