Are you thinking of G5B10 ? - What percentage of power loss would result from a transmission line loss of 1 dB? A. 10.9 percent B. 12.2 percent C. 20.5 percent D. 25.9 percent I have NOT memorized the Log tables, but that's an easy one to see. Using one more extension of your well known 3dB rule, and comparing it to 10dB, 25% for increase and 20% for decrease is elementary school in your head math. I followed a path very similar to your own. Different reference material though. Anyone with an ounce of curiosity continues to learn long after they get any license.