Euler's number

Etymology
Named after Swiss mathematician (1707–1783), who did, however, not discover it, although he likely gave the constant its modern symbol $$e$$.

Proper noun

 * 1)  The mathematical constant e, the base of the natural logarithm; an irrational, transcendental number approximately equal to 2.71828.

Usage notes
Should not be confused with, which often refers to other constants, most notably the $$\gamma$$ (also known as the Euler–Mascheroni constant).

Translations

 * Finnish: