Suppose if someone asks you to answer what day of the week was 14 November 1974, which happens to be his birthday, you will be puzzled. It would be a tough job to answer if you are not familiar with the method.
The present calendar we follow is called the Gregorian calendar. In this chapter, we discuss about the evolution of calendar and the rules adapted in the formation of present calendar.
We all know that there are seven days in a week. So, the day of the week repeats after every seven days. If today is Monday, then starting with Tuesday, the seventh day will be again a Monday. When the total number of days in a given period is divided by 7, the remainder we get is called the number of odd days. In other words, the number of days over and above the exact number of weeks, in a given period, is called the odd days.
We know that a normal year has 365 days. So, the number of odd days in a normal year is 1. (365 days means 52 weeks and 1 day.) If a particular normal year starts with Monday, it is obvious that the next year will start with Tuesday (if we count one odd day from Monday we get Tuesday).