# Today (Apr 12) is e day.

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wbport
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12 Apr 2019, 8:48 am

It's easy to celebrate pi day, it's 3/14 since its value is 3.1415926535... . However, the Euler (or Napier) constant "e" is 2.718281828459045... and it's harder to find a day to celebrate it since February has a lot fewer days than 71. Seventy-one days after the end of January is today, April 12, or the 71st day of February.

Celebrate appropriately.

Fnord
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12 Apr 2019, 9:06 am

Actually, the 0.7182818284590452353602874713527th day of February is the 11th.

So 2019/2.7182818284590452353602874713527 is February 11, 2019, at about 02:41:07.399 in the morning.

Another important value derived from e is 0.63212055882855767840447622983854 = (e-1)/e = "Tau". This represents what's known as the "Exponential Decay Constant" in physics and the "Time Constant" in electrical engineering.

Happy eDay!

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“I must acknowledge, once and for all, that the
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wbport
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12 Apr 2019, 10:55 am

Fnord wrote:
Actually, the 0.7182818284590452353602874713527th day of February is the 11th.[/b]

Please explain. The 0.718.. th day of Feb looks like it is on the first.

This can find the midpoint between date-times as well as add or subtract a constant to a date-time. MidPoint.htm

Fnord
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12 Apr 2019, 2:00 pm

e = 2.7182818284590452353602874713527

(e - 2) = 0.7182818284590452353602874713527

If 2 is the second month, then 0.7182818284590452353602874713527 is just a little over 7/10s into the second month.

(Hmm ... you're right ... that does seem a little off ... I'll re-run the numbers ...)

The second month is 28 days long.

28 x 0.7182818284590452353602874713527 = 20.111891196853266590088049197876

So that's actually the 20th day of the 2nd month, a little over 1/9th of the way through the day, or 02:41:07.399 in the morning.

Final Answer: 2019/02/20 at 02:41:07.399 Ante-Meridian.

_________________

“I must acknowledge, once and for all, that the
purpose of diplomacy is to prolong a crisis.”

— Leonard Nimoy as Mr. Spock, in the Star Trek
episode "The Mark of Gideon" (ep. 3.16, 1969)

wbport
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13 Apr 2019, 8:20 am

If you did pi day the same way, wouldn't it be around March 3? 0.1415926535897932384626433832795 * 31 .