Shyam Sunder Gupta

What is the longest year in history? Did you know there is at least one Friday the 13th every year? How many Friday the 13ths can occur in a single year? Interestingly, the dates 4/4 (4 April), 6/6 (6 June), 8/8 (8 August), 10/10 (10 October), and 12/12 (12 December) all fall on the same day of the week in any given year. What are leap years, and why does February have fewer days than any other month? Did you know that February 30th existed in Sweden for a short period?

A calendar is a system of measuring and recording times in terms of days and years. Have you ever thought about how life would be without a calendar? Many different types of calendars were developed and used by people in various parts of the world. 
Most ancient calendars, including those of Greece, were based on lunar months, so it was necessary to insert extra months to align the calendar with the seasons.

The ancient Egyptian calendar date was based on the solar system, which had a 365-day year, unlike the Babylonians, Greeks, and early Romans…read more on NOPR