We will only look at the scales on the reverse side of this slide rule since they are the ones of interest and are not found on other slide rules. The pictures below show different sections of the slide rule; starting with the far left and far right. You can clearly see the condensed scales and the DN scale, this scale represents the relationship between the number of zeros, number of digits and number of factors for the numerator and denominator. This scale is later referenced by the RN-DZ scale. Both the DN and RN-DZ scales have evenly spaced graduation marks.

Left end of the slide rule.

Right end of the slide rule.

Below is a reduced picture of the upper and lower stators. You can see clearly the four condensed C scales at the top and the four marked regions. These regions basically keep track of the order of magnitude of the the result. The bottom stator has the RN-DZ scales for calculations and those for the square root and cube root scales. The RN-DZ scales will determine the number of digits before the decimal point or the number of zeros after the decimal point for a specific calculation.

Upper and Lower Stator.

The slider (below) has condensed D, T, ST and S scales at the left and right. The left is for operations involving multiplication and the right is for operations involving division. The major DN scales is at the bottom of the slider.

Slider.

Finally, the picture below shows the detail of the middle of the slide which gives the digits or zeros for sine and tangent along with other instructions to calculate the difference number (DN) etc..

Middle section of the Slider.

 

The formula above is D - (F + Z), these symbols will be explained using examples.

Proceed to Explanation of Digits and Zeros