1,287. The Length of a Solar Year

Hilchos Kiddush HaChodesh 9:1

Regarding the length of a solar year, some Sages said that it is 365 days and one-quarter day, the quarter being six hours; others said that it is slightly less than that. The scholars of Greece and Persia likewise disagreed in this matter.

Hilchos Kiddush HaChodesh 9:2

According to the opinion that a solar year is 365 and one-quarter days, this leaves one hour and 485 chalakim remaining after each 19-year cycle, as was noted in halacha 6:10. The time between the start of each season and the next is 91 days, 7 and a half hours. If you know the date and hour when one season starts, you will be able to calculate the start of the next season, the one after that, etc. ad infinitum.