Complex sentence: There he formulated the Shoushili calendar (授時曆) in 1280 and calculated the year to be 365.2425 days, only 26 seconds off the real time; this is the same as the Gregorian calendar, but 302 years earlier.
Split into simpler sentences: There he formulated the Shoushili calendar (授時曆) in 1280 and calculated the year to be 365.2425 days, only 26 seconds off the real time. This is the same as the Gregorian calendar, but 302 years earlier.