For example, to calculate 3*2, the 1 on the top scale is moved to the 2 on the bottom scale.The answer, 6, is read off the bottom scale where 3 is on the top scale.Method 3 has the advantage that it only involves two scales.
The relative position of other marks can then be observed.
Numbers aligned with the marks give the approximate value of the product, quotient, or other calculated result.
There is more than one method for doing division, but the method presented here has the advantage that the final result cannot be off-scale, because one has a choice of using the 1 at either end.
In addition to the logarithmic scales, some slide rules have other mathematical functions encoded on other auxiliary scales.
Others feature scales for calculating hyperbolic functions.
On linear rules, the scales and their labeling are highly standardized, with variation usually occurring only in terms of which scales are included and in what order: "folded" versions of the C and D scales that start from π rather than from unity; these are convenient in two cases.
Some slide rules have been made for special use, as for aviation or finance.
Those slide rules have special scales for those applications, as well as normal scales.
The cursor can also record an intermediate result on any of the scales.