Last evening on the Food Network show, "Good Eats." Really. Alton Brown, science-y nerd chef waved a slide rule frenetically as he commented on figuring the math of declining ratio of water required to boil larger amounts of rice, in "Power to the Pilaf." As a combination of late-night (11pm+) viewing surprise and quickness of the joke, couldn't see the rule type. He's done this in at least one other episode, but I don't remember which.