## History of Calendars

### The History, Science and Mathematics of Indian (Hindu हिंदू*) *and Other Calendars

### A book by Rajesh Kumar Chopra

Multiple calendar systems are being followed in this large country, India, with diverse cultures; and though each of them is individually accurate based on its adopted principles, the difference is not easily understood due to mingling of them over many centuries. Another highlight of the confusion is the names of the months being same in most of the Hindu calendars.

A festival falling on different dates in different years is a common feature of all religions. For Hindus, the Hōlī Festival may occur on any day from March 1 to March 29; for Muslims the Īd may happen on any day of the year; whereas for Christians, the Easter Sunday may occur from March 22 to April 25 or as celebrated by some orthodox churches from April 3 to May 10. This does not happen arbitrarily, but there is Simple Science and Mathematics behind this.

Before going through the chapters, one must understand that the simplicity is not the Nature’s nature. Though the Nature follows its set of rules, it does not like round numbers, as it has an affinity to fractions and variations. Take the example of the ratio between the circumference of a circle to its diameter. It is denoted by a Greek Letter Pi (π) which is an irrational number, i.e. its value cannot be expressed exactly as a fraction or decimals. Though you can do some approximations, like 22/7 or 355/113, or say, represent it till 10 digits as 3.14159265359. People have calculated its value even till the 2,000,000,000,000,000th digit.

It would have been wonderful if we had exactly 4 weeks in a month. Counting of weeks would have been so much easier. Or each month could have been only of 30 days, a year of 360 days, and of course, no leap year. A lot better would have been a year of 100 days and 10 month in a year. But it is not. And therefore, I am writing this book with the objective of making the subject easy to understand. You may use your discretion in case of any difference of opinion or if you find any inconsistency which could have crept in inadvertently while collecting facts and figures from different sources. I have also used हिंदीHindī spellings (देवनागरी Devanāgarī script) for some words for Indian readers.

I also acknowledge the other scholars, whose views and citations have been indirectly reflected in this book. Brought to my knowledge I shall be happy to include their reference.

The objective of writing this book is to make people understand the calendar rather than to Re-Search.

I would highly appreciate all the suggestions and comments for any improvement.

**RK CHOPRA**

Read related Article