Verse:Irta/Trician Jewish calendar

One Trician lunar month is 30.58122882574347 Trician days long; hence months in the lunar calendar usually have either 30 or 31 days. Twelve lunar months are about 366.97474590892164 days, which exceeds the solar year by 9.89409312183100 solar days. Being a lunisolar calendar like our Jewish calendar, the Trician Jewish calendar removes a month (Marcheshvan?), approximately once in every 3 years, to keep the months aligned with the solar year.

(Passover falls on Nissan 15, which is required to be the first or the second full moon after the spring equinox.)