What is ln of 0?

Ln(0) is undefined because the natural logarithm function is only defined for positive real numbers. The natural logarithm of a number x is the power to which the base e (approximately equal to 2.71828) must be raised to obtain the number x. Since there is no value that e could be raised to in order to get 0, ln(0) is considered undefined. In mathematical terms, ln(0) approaches negative infinity as x approaches 0.