When I took college physics back in 1971, we had to master the ways of the slipstick, the good old reliable slide rule. I grew up around these interesting devices, as my dad's profession was that of a mechanical engineer. These logarithmically-scaled tools of mathematicians, engineers and physicists are quite interesting once you understand what is going on, and how logarithms allow you to perform a variety of calculations.
No, the precision of a modern calculator isn't there; you had a limited number of decimal places for precision, and often had to derive numbers as scientific notation. You also had to keep up with where the decimal place was so as to get the correct mantissa. This resulted in two types of professors: those who gave partial credit for answers derived using the slide rule, but with the decimal misplaced; and those who counted the entire answer wrong, even if you had the right digits.
At first, many schools and testing centers were slow to embrace new technology, eschewing the use of electronic calculators, and requiring proficiency with the slide rule. Eventually, the precision and ease of calculators won out, and the slide rule quickly exited the scene, both in academia and in the business world.
Back in my college days, a simple four function calculator was still a novelty, and sold for around one hundred U.S. dollars. Today, you can get them for 99¢ at Wal-Mart, and they don't even need batteries, running instead on light.
If you want to try your hand as a slide rule and don't have one, don't worry. Just CLICK HERE to find links to seven different virtual slide rules, along with instructions and tricks you can do with these remarkable little marvels. Or just CLICK HERE to go directly to one of them. This is about the coolest web application I have seen! Just drag your mouse to move the sliding part or the glass cursor, and you are computing.