Re: OT  slide rules Message #5 Posted by hugh steers on 16 Apr 2006, 9:20 p.m., in response to message #1 by Don Shepherd
For a while now, i've been using a slide rule for real world use! not as a calculator replacement, but i've found some situations where a rule works really well.
i've taken to carrying around a small 5 inch pocket rule. i quite like the pocket sizes rules. the one i've been carrying is a pickett. this isnt the best pocket rule either; i have a K&E and a Faber Castell that are both nicer, better made and more comprehensive – the picket is just smaller and not very rare or valuable.
anyway, here are my uses. (1) i've noticed that restaurants are dark and there’s almost always a prime number of people to divide by. since the number is usually between 3 and 13, these are all easy on a rule and it gives me an “analogue” result which i ignore anyway and scan forward to the next major division and call that the answer.
(2) supermarkets have taken to making “special offers” sometimes worse value than before. to compare price/quantity ratios on a rule is easy, take the first price, divide by first quantity and multiply by second quantity. compare answer to second price. the dividemultiply is easy on a rule because you don’t worry about the intermediate result – you just slide forward. even quicker is that you often know whether the result is better or worse simply by the direction of travel of the slide on the final multiply. in which case you don't even bother to line it up (assuming you just want a comparitor).
its not worth carrying a 10 inch rule about for these because 2 figure accuracy is fine for this kind of thing. the one thing that i would like tho’ is a 5 inch rule with a folded multiply/divide scale (ie 10 inch precision) but no advanced scales (trigs, logs etc), otherwise it would be too fat.
so there.
