LOG

LOG(number [,base])

Returns the logarithm of a number to any base.

number	The number you want the logarithm of.
base	(Optional) The base of the logarithm.

REMARKS

* If "number" < 0, then #NUM! is returned.
* If "number" is not an integer, it is truncated.
* If "base" is left blank, then 10 is used.
* If any of the arguments are not numeric, then #VALUE! is returned.
* You can use the LOG10 function to return the logarithm of a number to the base 10.
* You can use the LN function to return the natural logarithm of a number (to the base e).
* There is no equivalent VBA function.
* There is a VBA function called LOG but this is the equivalent of Excel's LN function.
* The natural logarithm is the logarithm to the base e. The constant e is approximately 2.718282.
* There is a VBA function with the same name VBA.LOG but it does something completely different.
* For the Microsoft documentation refer to support.microsoft.com

	A
1	=LOG(12) = 1.08
2	=LOG(10) = 1
3	=LOG(10.9) = 1.04
4	=LOG(8, 2) = 3
5	=LOG(16, 2) = 4
6	=LOG(86, 2.7182818) = 4.454
7	=LOG(-16, 2) = #NUM!
8	=LOG("some text") = #VALUE!
9	=LOG(12, "some text") = #VALUE!