Non-logarithmic Slide Rule
This Demonstration illustrates multiplication by two non-logarithmic slide rules.[more]
In the first case, define . Then . This slide rule has the four scales , , , and .
In the second case, define . Then . This slide rule has the four scales: , , , and , but and can be considered the same.
When , read on the bottom scale below on the scale.[less]
 J. Bryant and C. Sangwin, How Round Is Your Circle?, Princeton, NJ: Princeton University Press, 2008 pp. 247–248.