NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2021 Nov 16, 09:15 0800
Hello!
To refresh my longforgotten ability to use logarithm tables I recreated the fourplace one I used at school  by W.M.Bradis. (beware of typos in the scanned edition! my recreation is more reliable :D )
Then I tried to solve the division step of some allHaversine azimuth calculation  which involved the divident == 0,2410 and the divisor == 0,3271.
0,2410 = 2,410·10^{1}; 0,3271 = 3,271·10^{1}
These "minus one" powers of ten mean that the logarithms of both numbers will have the "bar one" prefixes further denoted as "/1".
log(0,2410) = /1,3820; log(0,3271) = /1,5146
Now the subtraction step:
/1,3820

/1,5146
______
/1,8674
The resulting "bar one" prefix is born when I borrow from the minuend's characterisic digit  the "minus one", making it "minus two", then subtrahend's "bar one" changes its' sign and becomes "plus one": 2 + 1= 1, thus the "bar one" in the result.
Note that the fractional part is exactly the mantissa of the result, ready to be reverselookedup in the table  for exponentiation.
Now exponentiating the resulting mantissa (the 0,8674) I get 7,369. The "bar one" characteristic means that the result actually is 7,369·10^{1}, or 0,7369.
This is how I did calculations until electronic calculators and computers made me lazy and stupid...
I wonder how the "10+" logarithms would work in this example?
Warm regards,
Tony
60°N 30°E