240 months. There are 12 months in a year, 20 years from 2003 to 2023, and 20 times 12 equals 240 months. In, it was first seen in Oracle Bone Inscriptions, and its original meaning is "year ripe and five grains ripe", namely "Shuo Wen Jie Zi": year ripe and five grains ripe. It is equivalent to a year's harvest, year, festival, year and year, and it is also a time unit, which refers to the period of about 365 and 1/4 solar days required for the earth to orbit the sun once.