LN is one of the vital Numeric/Math functions of Oracle. It is used to get the natural logarithm of a number. The LN function is supported in the various versions of the Oracle/PLSQL, including, Oracle 12c, Oracle 11g, Oracle 10g, Oracle 9i and Oracle 8i.
LN( number )
number: It is used to specify the number whose natural logarithmic value will be calculated, where number is always greater than 0.
The value of natural logarithm of 5 is 1.60943791243 and so is the result.