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 Subject: Unconventional use (addition) for the standard sliderule. Category: Science > Instruments and Methods Asked by: hlf-ga List Price: \$25.00 Posted: 14 Jul 2002 12:43 PDT Expires: 13 Aug 2002 12:43 PDT Question ID: 39521
 ```Many years ago I learned how to do addition on a standard sliderule. My engineering colleagues were always astonished when they were shown this possibility as it is counter-intuitive. The basic sliderule operation is to add logarithms. I have been wracking my brain trying in vain to reconstruct the very simple process by which normal addition can be performed on the standard sliderule. Does anyone out there know how to to this?```
 Subject: Re: Unconventional use (addition) for the standard sliderule. Answered By: silviares-ga on 14 Jul 2002 13:36 PDT Rated:
 ```Hello there are many resources about sliderules on the web and I found it quite overwhelming being that I have never used a sliderule myself. But I found this on one of the sliderules newsgroups "...I would like to mention again the only simple and easy procedure that I know of performing sliderule addition (although I never used it): a + b = a (1 + b/a)" (http://groups.yahoo.com/group/sliderule/message/4818) Is this what you where remembering or looking for ? Another newsgroup addressing sliderules addition issues is http://slashdot.org/articles/01/07/07/156226.shtml I also found some interesting resources at http://www.sliderules.clara.net/index.htm and http://www.sliderule.ca/ Hope this helps silviares``` Request for Answer Clarification by hlf-ga on 14 Jul 2002 14:53 PDT ```I could not find the comments icon! This is intended as a comment to be helpful to others interested in the subject. The full process for doing addition on the slide rule, thanks to the hint provided by silviares, follows: a + b = a (1 + b/a) So we first perform the division operation by placing A on the C scale over B on the D scale and reading the ratio (b/a). We mentally add 1 to the result and move the index ("1") of the C scale over the result (1 + b/a). Then we look under A on the C scale to find the result [a(1+b/a)] immediately underneath on the D scale.``` Clarification of Answer by silviares-ga on 14 Jul 2002 16:25 PDT ```Since hlf-ga couldn't find the comment icon and he posted his comment as a request of clarification I have been called by Google Answers to clarify. There is not much that I can add. Thank you to hlf-ga for detailing the addition process. As I said I have never used a sliderule myself but I know enough math to see that it made sense and that hlf-ga would have know exactly what to do. I provided a couple of links of newsgroups in case the method was not the one he remembers and in case he wanted to post the question to the newsgroup himself. The last two links in my answer were mostly to satisfy eventual curiosity - and were pretty interesting to read and were rich in pictures and documentation for old sliderules. Thank you again, silviares```
 hlf-ga rated this answer: ```The response was close to what I sought and was sufficient for me to work out the rest by myself. Only the first link was helpful. I would have preferred a complete solution, but this answer was sufficient justify payment in full. I was very pleased by the speed with which the answer was forthcoming. Previously I had tried "Ask Dr. Math" without success. So, bravo for Google Answers and silviares-ga. Additional comments would be welcome. Howard```

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