But a more interesting alternative is a calendar of 13 four-week months for a total of 364 days, plus one or two days, without systemic names or dates, that are

But a more interesting alternative is a calendar of 13 four-week months for a total of 364 days, plus one or two days, without systemic names or dates, that are inserted during a year. Each month has four weeks of seven days, 28 days altogether, 13 * 28 = 364. Guess what the drawback is? If months and weeks start on canonical days (i.e. 1 and Sunday), every month has a Friday the 13th. :)