E is an infinite acyclic decimal with an approximate value of 2.7182818284 59045 23536 02874 71352 66249 77572 47093 6995 95749 66967 62772 40766 30353 5477.
As a mathematical constant, e is the basis of natural logarithmic function. Sometimes called Euler number, named after the Swiss mathematician Euler; There is also a relatively rare name Napier constant to commemorate the introduction of logarithm by Scottish mathematician John Napier. It is one of the most important constants in mathematics, just like pi and imaginary units I and E.
The history of e can be traced back to a long time ago. The first mention of the constant e is a table in the appendix of John Napier's logarithmic works published in 16 18. But it didn't record this constant, only a list of natural logarithms based on it, which is generally believed to be made by William Oughtred. It was Jacob Bernoulli who first thought that e was a constant.
The earliest known uses of the constant e are 1690 and 169 1 year, which is represented by B. In 1727, Euler began to use e to represent this constant. The first use of e in publications is Euler mechanics in 1736. Although some researchers later used the letter C, E was widely used and finally became the standard.
The reason why E is used is really unknown, but it may be because E is the first letter of the word "index". Another view is that A, B, C and D have other common usages, and E is the first available letter. However, it is unlikely that Euler chose this letter because it is the initials of his own name, because he is a very modest person and always properly affirms the work of others.
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