~ Oscar Wilde on the Slide Rule
The slide rule is a completely fictitious computational device. This is not so much to say that it is a computational device that is fictitious, instead it is a device that provides fictitious computations. In a time before the calculator, many claimed that slide rules were capable of performing any mathematical functions that one could need to perform. These went beyond addition and subtraction, but also included logarithms, which are also, in point of fact, completely fictitious. In fact, the only way that logarithms were ever computed were on slide rules, with the answers being completely made up, and often completely random and unrepeatable. When slide rules were in wide use, the only actual way to add or subtract were to count fingers and toes, thus limiting numbers to only 0-20 for women, and 0-21 for men.
Now that we are in a more enlightened time that includes computers, calculators, and internet porn, we can add and subtract in a much more efficient manner, as computers are outfitted with several million, or even trillion, fingers and toes. Slide rules are now only an artifact of a bygone and ignorant age. Anyone who claims proficiency with the use of a slide rule should be considered clinically insane, and avoided at all costs. Should you encounter someone actively using a slide rule, the wisest course of action is to not come within 10 feet, as users are known to become confused and even violent when approached with even the simplest four-function pocket calculator, and those slide rules can have sharp corners. Instead, you should remain calm, not attempt to engage them in any conversation, hide any modern computational devices you have, and contact your local mental care facility.