We had a graduate engineer who, during extended Boeing structures training in Seattle, acquired an FAA PPL. One day, when we were discussing magnetic variation over a cup of tea, the matter of runway numbers came up and we pondered over the possible need to renumber runways. "So runway 11 would be heading 110 and the other end would be runway 29, heading 290? I always wondered where the numbers came from." he said. Doh!