The week of 16 in 2022 is from April 1 1 to April 17. The use of weeks as a time period originated in Babylon. According to the change of the moon, the Babylonians set seven days as a week, also called a week. At present, the system of seven days a week, which is widely practiced all over the world, was first formulated by the Roman emperor Constantine the Great, and announced that seven days is a week. This system has been used to this day.