People all have such common sense that there are different months in the Gregorian calendar, that is, there are such provisions in the Gregorian calendar months: "April, June, September and 165438+ 10 have 30 days, and other months have 3 1 day, except for February, which has only 28 days." The size of the moon began in Caesar's time in the Roman Empire. At that time, Caesar sent someone to modify the calendar and enacted the julian calendar Law, stipulating that all months with special religious significance are 365,438+0 days, and all unimportant months are 30 days. Therefore, the month of 1, March named after the god of war, and July named to show respect for Julius Caesar all have 3 1 day. Because February is an unlucky month for executing prisoners, there are only 29 days. Julius Caesar's successor Augustus named Augustus after himself. In order to be on an equal footing with Caesar, he asked to increase August to 3 1 day. In order to make August have 3 1 day, he borrowed another day from February and reduced it to 28 days. In order to avoid the connection of the three big months, it is stipulated that September and 165438+ 10 each have 30 days, and 10 and1February are extended to 3 1 day.