# PLSQL | LN Function

The LN function is an inbuilt function in PLSQL which is used to return the natural logarithm of a given input number. The natural logarithm of a number is the logarithm of that number to the base e, where e is the mathematical constant approximately equal to 2.718. This is written using the notation lnx and also some time as logex.

Syntax:

`LN(number) `

Parameters Used:
This function accept a parameter number which is the numeric value used to calculate the natural logarithm. This number should must be greater than 0.

Return Value:
This function returns the natural logarithm of a given input numeric value.

Supported Versions of Oracle/PLSQL:

1. Oracle 12c
2. Oracle 11g
3. Oracle 10g
4. Oracle 9i
5. Oracle 8i

Let’s see some examples which illustrate the LN function:

Example-1:

```DECLARE
Test_Number number := 20;

BEGIN
dbms_output.put_line(LN(Test_Number number));

END;  ```

Output:

`2.99573227355399`

In the above example, 20 is the numeric value whose natural logarithm value is 2.99573227355399

Example-2:

```DECLARE
Test_Number number := 25;

BEGIN
dbms_output.put_line(LN(Test_Number number));

END; ```

Output:

`3.2188758248682`

In the above example, 25 is the numeric value whose natural logarithm value is 3.2188758248682

Example-3:

```DECLARE
Test_Number number := 100.5;

BEGIN
dbms_output.put_line(LN(Test_Number number));

END; ```

Output:

`4.61015772749913`

In the above example, 100.5 is the numeric value whose natural logarithm value is 4.61015772749913

This function is used to find out the natural logarithm of a given input number.

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