Don Sheriff's garage is not for automobiles. The only motor you are likely to hear running at his midtown Tulsa home is from his DeWalt Scroll Saw, which the 84-year-old uses to make jigsaw puzzles.

I have a stripy flag laid out on my desk. The stripes are all of equal width, five of them in total. Because three of the five are blue, I know that three-fifths of the flag is blue. However, I take ...