Hot answers tagged kiddush-hachodesh
It has been used 11 times so far since the enactment of the fixed calendar in 4119. It was used in 4179, 4257, 4504, 4602, 4849, 5096, 5194, 5441, 5519, 5688, and 5766. The next time it will be used is 6013 if we still have a fixed calendar then. You can read about this exceedingly rare Dechiya and its history here.
The Rambam is trying to explain how the end of the year "drifts" across the days of the week. The lunar year (twelve lunar months) is roughly 354.3 days. 350 is divisible by seven (hence "groups of seven"), so the only thing that decides what day of the week the year ends on is the remainder. --- the extra 4.3 days. Thus, if the end of the previous year ...
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