The logarithm of a number using base e (which is Euler's Number 2.71828...)
It is how many times we need to use e in a multiplication to get our desired number.
Examples:
• the natural logarithm of 7.389 is about 2, because 2.718282 ≈ 7.389
• the natural logarithm of 20.09 is about 3, because 2.718283 ≈ 20.09
Often abbreviated as ln
