Website last updated 03 August, 2010

C Scale

This reference covers both the C and the D scales.

The C scale is the main multiplicative scale on the slider, identical to D, its counterpart on the stock. C and D are used together to perform the most important functions of the slide rule: multiplication and division. All other scales implicitly refer in some way to C and D.

read the tutorial on multiplication and division

C ranges between 1 and 10, but the decimal point is not fixed, and you may imagine it runs from 0.1 to 1, 100 to 1000, etc, depending on your actual numbers.
Scale markings
You won't find leading or trailing zeros, nor decimal points, nor negative values, anywhere on C. These are for you to fill in. Looking at the scale markings on C, you will see sequences such as 2, 25, 3. If you are working with the number 217, you would interpret those markings as 200, 250, 300, and find 217 among them. If you are working with the number -2.17, you would interpret the same sequence as -2, -2.5, -3, and find -2.17 in there. Notice that even the 10 on the rightmost side is marked as 1.