I own a few slide rules, and know how to use (most of the) scales on them. I keep one
of my favorites on my desk at work, and even use it occasionally. (If you care, it's
currently a late-model K&E 4081-3 LogLog Duplex DeciTrig, "like my Dad used to use",
although it is sometimes a Post 1461 Versalog. I own a plastic DeciLon and a beautiful
plastic Faber 2/83N and an aluminum Pickett or two and a few others, but I like the
classic laminated wood rules. Somehow they just FEEL like precision instruments.)

My work doesn't call for much on-the-fly number-crunching, and I find that my slide
rule that actually gets the most use is a Concise 28N, a little pocket-sized plastic
disk that hardly even looks like a slide rule. As a result, it's easieast to carry
with me everywhere, and easiest to hold in one hand and shift the inner disk with my
thumb. It's a snap to figure gas mileage, restaurant taxes and tips, or the cheapest
cereal or cat food or just about any bulk grocery items.

I own calculators too, a high-end model with more buttons than I understand, and even a
cheapie with just the basic functions. And they get used at the appropriate times. But
their UI is very ill-suited to the task of quickly evaluating bulk food prices while
pushing a shopping cart. My pilot friends tell me the same thing, that their onboard
computer is capable of computing airspeed, fuel consumption and lots of other things,
but that their round E6-B is their favorite tool for such calculations because it's far
easier to use with one hand while flying the plane with the other.

People talk about the importance of slide rules, tradition, math skills and the elusive
"feel" of numbers and their precision and magnitude. And they're right, these are all
important skills that I still wish were emphasized more in school. But it seems to me
that the thing that's overlooked the most is the importance of selecting the appropriate
tool. You wouldn't swat a fly with a bazooka, and you wouldn't use a slide rule to
balance your checkbook. But they're perfect for lots of calculations, and it really is
a shame that they have become so marginalized.

The right tool for the right job!