Sanhedrin 18A

מאתים ושבעים ושבעה.

The number of people needed in a city for it to be eligible for a lesser Sanhedrin is 277. This number is based on the opinion of R' Neḥemya, who requires 230 men, but requires an additional 47 men in case it happens that the rabbis of the court reach a situation where they are not able to arrive at a verdict, and pairs of judges need to be added, potentially increasing the number of judges on the court from 23 to 70, a maximum of 47 additional judges.

והתניא, רבי אומר: מאתים שבעים ושמנה! לא קשיא: הא ⁠– רבי יהודה, הא ⁠– רבנן.

The Talmud asks: But isn’t it taught in a baraita that R' Yehuda HaNasi says: The number of men needed in a city for it to be eligible for a lesser Sanhedrin is 278? The Talmud answers: This is not difficult. This baraita that said R' Yehuda HaNasi requires 277 residents is stated in accordance with the opinion of R' Yehuda, who holds that there are 70 judges on the Great Sanhedrin, and this baraita that quoted the number as 278 is stated in accordance with the opinion of the Rabbis, who hold that there are 71.

תנו רבנן: ״ושמת עליהם שרי אלפים שרי מאות שרי חמשים ושרי עשרת״. ״שרי אלפים״⁠ – שש מאות, ״שרי מאות״⁠ – ששת אלפים, ״שרי חמשים״⁠ – שנים עשר אלף, ״שרי עשרות״⁠ – ששת ריבוא. נמצאו דייני ישראל שבעת ריבוא ושמונת אלפים ושש מאות.

Apropos the opinion of R' Neḥemya, which links the issue of the lesser Sanhedrin with the appointment of the ministers in the wilderness, the Talmud relates: A baraita states: The verse states: “And place over them ministers of thousands, ministers of hundreds, ministers of fifties, and ministers of tens” (Exodus 18:21). The number of ministers of thousands was 600, as there were 600,000 men in total; the number of ministers of hundreds was 6,000; of ministers of fifties, 12,000, and of ministers of tens, 60,000. Therefore, it is found that the total number of judges of the Jewish people was 78,600, and suitable people were found to fill all of these positions.