Calendar Math

Do you know our modern calendar (New Style / Gregorian) day and date repeats itself every 28 years and there is a sequence. It is worthy to note that the leap year repeats every 28 years and normal years every 11 or 6 years.

Excited want to know more about the math then continue

How it Started

I was watching and showing my kids videos about mathematics, how one is able to do faster than calculator. I will plan to touch the Vedic (vega meaning Faster) Mathematics in my next articles. Below is the video from TEDx where Mr. Arthur Benjamin does a phenomenal job and he even passes on his phone with an app to find the day of the week

Below is the video of Ms. Shakuntala Devi, doing calculations at lightning speed, probably faster than a computer. She as well during this video answer day of the week for the particular date

There is math behind how it is calculated and I knew that from my school days...

Now comes my turn, I asked my kid to ask me the date (falling between 2020 year to 2030 ) and I will respond him with the day. He was amazed that I was able to do some math and answer the day without any mistakes.

Math behind finding day

I have tried to explain my way of doing it here, hope you find it interesting

Step1: Find the 12 digit code

Step 2: Find day using the code

Step 3: Finding or decoding the entire sequence

We know that for 1year has 365 days which is remainder is 1, the day gets incremented next year. If it is a leap year then the remainder is 2, then the day incremented by 2 from March to Feb of subsequent year.

Below is the link to my file in one drive, where you can find the 12 digit code from 1993. Thanks to Microsoft Excel for the formulas, you made it easy

Conclusion

1. From the excel file, one can find that there are 14 different code (Column O - Find Unique / Sequence)
2. The code follows a sequence (Column O - see colored markings) and is repeated every 28 years.
3. The difference between the first occurrence and subsequent occurrence is either 11 or 6 or 28 years. See it in Column Q (Find Diff)
4. If we have to take a leap year as a reference then the repeat is 11, 11, 6 which sums to 28 years

Hurray!! find it interesting, leave your comment about this article.

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