Two by two.........2.7...........could be seen as a 2, and a 7........both are prime by the way...............then comes 18.................2 + 7 = 9............1 + 8 = 9..........


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.
And Euler is spoken like "Oiler"