cantoresq – the calendar of Hillel is indeed based on Rav Ada’s calculation that there are 235 lunar months in 19 solar years. Rav Ada’s calculation is not exact either, but overestimates a year by slightly more than 6 minutes (Rav Ada’s calculation is 365 days, 5 hours, 997 and 48/76 Chalakim).
asdfghjk: Argh, another imposter.