I think I've got the decimal places figured out for multiplication on the slide rule. First you convert the numbers to scientific notation (e.g. 123=1.23×10²) then you add the exponents together, and if one of the following occurs you add an additional 1 to the exponent:
1. Using the C/D scales, you needed to use the right index for the multiplicand or you used the left index, then went off scale and had to jump to the CF/DF scales. (If you used the right index and went off scale and had to switch to the CF/DF scale, you do NOT add the additional 1 to the exponent.)
2. Using the CI/D scales, you had to use the left index to find the answer.
3. Using the A/B scales, the answer was in the second decade (10-100).
4. Using the K scale, the answer was in the second decade. If it was in the third decade (100-1000) add 2 to the exponent instead.
I think division will be similar but with subtraction.
I don't have any instructions for this, I'm having to figure this stuff out on my own.