Activities/Sliderule

How to use a slide rule

There are three parts to the slide rule: (1) a fixed rule (either the D scale or the L scale); (2) a sliding rule (the A, C, or L scales); and a reticule, which moves independently of the rules.

To move the sliding rules, simply drag them. Also to move the reticule, drag it. (Note: The entire slide rule does not fit on the screen. By dragging on the fixed rule, you can scroll the canvas to reveal different sections.)

Most calculations on a slide rule require three steps:

1. position the end of the top slide above a number on the bottom slide;
2. position the reticule over a number on the top slide;
3. read the result from the bottom slide.

The Sliderule Activity displays these three values on tabs attached t the top slider and the reticule. The calculation is also displayed on the activity toolbar.

Multiplication

To multiply, first position the end of the C slide over one of the multiplicands on the D slide. Then position the reticule over the other multiplicand on the C slide. Read the result off of the D slide.

Example: 2 × 1.31 = 2.62

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  Position the end of the C slide over 2 on the D slide

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  Position the reticule over 1.31 on the C slide and read the results (2.62) from the D slide.

Division

Division is the opposite of multiplication. First position the reticle over the divisor on the D slide. Then without moving the reticule, position the C slide so that the dividend is under the reticule. Read the result off of the D slide under the end of the C slide.

Example: 2.62 / 1.31 = 2

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  Position the reticule over 2.62 on the D slide. Position 1.31 on the C slide under the reticule.

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  Read the results from the D slide.