Most people are aware that Pi Day is celebrated on March 14, the calendrical day that most closely corresponds to the number π, which is approximately equal to 3.14159265.

Far fewer people know that today, February 7, is e-Day. That is, the day that corresponds to Euler’s constant, the base of natural or Naperian logarithms, which is commonly written as e.

e = 2.7182818 (approximately). If we use a bi-digital interpretation of the decimal portion of the number, as is done to calculate Pi Day, e-Day would be February 71, which might prove difficult to celebrate, even in a Leap Year.

However, even though it is considered heretical by certain orthodox mathematical sects to do so, if we take the 7 by itself as the significant digit (the uni-digital interpretation), e-Day becomes February 7. Choosing that date gives us a week to recover before the rigors of St. Valentine’s Day.

The rest of the digits might be read in several different ways. If we were to read them as a decimal fraction of the day, then they would represent 0.182818 × 24 hours, or 4.387632 hours, that is, about 4:23 am.

That’s a little earlier than most people want to get up for their e-Day celebrations. So I suggest reading the rest of the digits as 18:28:18, that is, 18 seconds after 6:28 pm. That’s right at dinnertime, which is much better.

Watch the clock! At eighteen seconds past 6:28 tonight, before digging into the Chateaubriand, everyone should raise a champagne glass and toast John Napier of Merchiston for his contributions to mathematics.