Number 13-class battleship Number 13-class battleship The "Number 13"-class battleship was a planned class of four fast battleships to be built for the Imperial Japanese Navy (IJN) during the 1920s. The ships never received any names, being known only as "Numbers 13–16". They were intended to reinforce Japan's "eight-eight fleet" of eight battleships and eight battlecruisers after the United States announced a major naval construction program in 1919. The "Number 13" class was designed to be superior to all other existing battleships, planned or building. After the signing of the Washington Naval Treaty in 1922, they were cancelled in November 1923 before construction
13 (number) 13 (number) 13 (thirteen) is the natural number following 12 and preceding 14. Strikingly folkloric aspects of the number 13 have been noted in various cultures around the world: one theory is that this is due to the cultures employing lunar-solar calendars (there are approximately 12.41 lunations per solar year, and hence 12 "true months" plus a smaller, and often portentous, thirteenth month). This can be witnessed, for example, in the "Twelve Days of Christmas" of Western European tradition. The number 13 is: Since 5 + 12 = 13, (5, 12, 13) forms a Pythagorean triple. There are 13 Archimedean