As has already been mentioned, when I took my Pilot's License the Cessena Student Kit included a Circular Rule, and was the standard tool used everywhere in Aviation. If you boarded an aircraft during the 1980's, you were depending on a type of Slide Rule to get wherever you were going safely; if you were flying a light aircraft you probably used one up until sometime in the last decade.
When I owned a retail store in an industry where discounts from MSRP were Standard Operating Procedure, we kept our Wholesale Price Lists at the front counter and staff made quotes and/or sales based on Cost Plus [our required margin]. The margin was based on paying all the bills and taxes and leaving between 5 and 10% as Net Profit for the year.
We used a Circular Slide Rule for that and other calculations, such as "We Pay The Tax" calculations to find the required retail price, the required Sales Tax amount, to, say, sell an item for $120 all in. And so on.
Our Retail stores used them up until the late 80's. With a manual entry sales invoice, a Cardboard Box for record storage (File Storage Boxes) and a Cash Box, we sold $Millions annually and had records of sales (e.g. for warranty work) for a decade that would fit in a closet.
We used Pocket Calculators to do addition/subtraction math, such as adding up the quote or writing the Sales Invoice. The "lack of precision" of the Rule made quotes much easier since you would get a visual representation of your cost plus margin, which made rounding to two or fewer decimal precision very easy.
One notable feature of the system was speed