1.618.........................the gold ratio............much like e..............2 18's....................twice 18 is like full circle...........18 + 18 = 36................

e (Euler's Number)

The number e is a famous irrational number, and is one of the most important numbers in mathematics.
The first few digits are:

2.7182818284590452353602874713527 (and more ...)

It is often called Euler's number after Leonhard Euler (pronounced "Oiler").

e is the base of the Natural Logarithms (invented by John Napier).
e is found in many interesting areas, so it is worth learning about.