Have a look (search) in the FAQ forums for more IP address help than you can shake a stick at.

Alternatively, go directly to the UDF forum and seach for IP/Subnet UDFs to do the job for you.

The quick anwer is:
Code:
$sThirdOctet=Trim(Split(@IPADDRESS0,".")[2])



However, I recommend that you look in the other forums for more info.