A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Date: 2016 Nov 9, 09:39 -0800
In the antiquated world of slide rules, there were no decimal places on the C and D scales. One of the first things you had to learn was how to estimate and where to place the decimal place.
( I'm tempted to expand on this but that would just dilute the basic answer. - - - Arrgh ! I can't stop myself! I think that estimating and thinking about the answer helped with understanding as opposed to plugging numbers into a computer program and assuming that the computer is correct. Now I'm done. )