260 (two hundred [and] sixty) is the natural number following 259 and preceding 261. It is also the magic constant of the n×n normal magic square and n-queens problem for n = 8, the size of an actual chess board. 260 is also the magic constant of the Franklin magic square devised by Benjamin Franklin. The minor diagonal gives 260, and in addition a number of combinations of two half diagonals of four numbers from a corner to the center give 260. There are 260 days in the Mayan sacred calendar Tzolkin. 260 may also refer to the years AD 260 and 260 BC.