Multiplication a · b
This is chiefly carried out with the main scales C and D of the front of the slide rule.
Example: 2.45 × 3 = 7.35
Set the 1 of the slide of the rule (C 1) above the 2·45 on the lower scale of the slide rule (D 245), move the cursor line ( Important : Whenever the cursor line is mentioned in this and the following chapters, this will always refer to the long, central hairline on the front and the back of the cursor. ) Into position above the 3 of the lower slide scale (C 3) and read the product . 7·35 . underneath the cursor line on the lower scale of the slide rule (D 735).
Multiplication with Scales A and B: see below
Example: 2.04 × 3.18 = 6.487. Place C 1 above D 2.04, place the cursor line above D 3.18, and read the result . 6.49 . on D, likewise underneath the cursor line.
Example: 11.45 × 4.22 = 48·35. Place C 1 above D 11.45, place the cursor line above C 4.22, and read the result . 48·35 . on D, likewise underneath the cursor line.
In calculations on the lower scales C and D it sometimes happens that with the setting C 1 above the first factor on scale D the slide projects too far to the right, so that it is no longer possible to set the second factor on C.
Transposing of the slide
Example: 7.5 × 4.8 = 36
in this case the slide is pushed to the left until the beginning C 1 is replaced by the end of the slide C 10 (marked 1) above the first factor on scale D.
This operation is termed transposing the slide. It can be avoided if, in case of need, C 10 (end of slide) is immediately placed above the first factor. An experienced user knows at once which method of setting to adopt, i.e. "beginning of slide, C 1, above first factor" or "end of slide, C 10 (marked 1), above first factor".
Examples for practice:
Setting: "Beginning of slide C 1 above first factor": 1.82 × 3.9 = 7.1; 0.246 × 0.37 = 0.091; 213 × 0·258 = 54·95
Setting: "End of slide C 10 above first factor": 4.63 × 3.17 = 14.68; 0.694 × 0.484 = 0.336
This operation of transposing of the slide is not necessary, in practical use, with the "x.displaced scales" CF, DF, in con junction with scales C and D (see below).