Find the natural logarithm of a number.
The natural log uses Euler's number e as its base, and appears throughout calculus and compound growth formulas.
ln(x): Logarithm base e (≈2.71828)
Why is e used as a base at all?
e comes up naturally in continuous growth. It is the base where the logarithm's rate of change is simplest, which is why it appears so often in calculus and finance.