# Understanding the basics of the slide rule

Basic Slide Rule Instructions To multiply two numbers on a typical slide rule, the user set the left index start of the scale on the C scale to line up with one factor on the D scale. All labels refer to Pickett scales. Scale labels were not completely uniform between brands. Simple Multiplication uses C and D scales Example: Move the cursor to 3. The cursor is on the D scale at 7. This is the answer. Move the cursor to 4. The cursor is now at 1. We can use the folded scales to get this answer.

The cursor is now at 3. The cursor is now at 5. Reciprocal uses C and CI scales Example: Trigonometry Sin x for angles between 5. The cursor is at 5. We know that the correct answer for a sin in this range is between 0. Cos x for angles between 5.

The cos scale shares the sin S scale. Instead of increasing from left to right like the sin scale, cos increases from right to left. The cursor is now at 8. We know that the correct answer for a cos in this range is between 0. Tan x for angles between between 5.

Move the cursor to 33 on the T scale. The cursor is now at 6. We know that the correct answer for a tan in this range is between 0.

## Find a copy in the library

Move the cursor to 63 on the forward T scale. This scale increases from left to right. Sin x and tan x for angles between 0. The cursor is now at 2. Sin x and tan x for other small angles using C and D scales For small angles, the sin or tan function can be approximated closely by the equation: Knowing this, the calculation becomes a simple division. This technique can also be used on rules without an ST scale.

We know that the correct answer is near 0. Square Root uses C and B scales Example:the concepts of the slide rule are examined. number scales, exponents, logarithms, decimal point estimation, and procedures used to multiply and divide on the slide rule are presented in . Knowing this, the calculation becomes a simple division.

This technique can also be used on rules without an ST scale. Example: calculate sin(°) Move the cursor to 3 on the D scale.

## Basic Multiplication

Slide on the C scale to the cursor. Most rules have a . understanding the slide rule. johnson, ronald e.; and others. a booklet designed for elementary school students to be used independently from and in addition to the regular classroom curriculum in mathematics is given.

the fifth- or sixth-grade student is presented with a discussion of the applications of the slide rule and with a background. The basic advantage of a circular slide rule is that the widest dimension of the tool was reduced by a factor of about 3 (i.e. by π). For example, a 10 cm circular would have a maximum precision approximately equal to a cm ordinary slide rule.

The slide rule made it easier to utilize the log relations by developing a number line on which the displacement of the numbers were proportional to their logs. The slide rule eased the addition of the two logarithmic displacements of the numbers, thus assisting with multiplication and division in calculations.

## How A Slide Rule Works

Knowing this, the calculation becomes a simple division. This technique can also be used on rules without an ST scale. Example: calculate sin(°) Move the cursor to 3 on the D scale.

Slide on the C scale to the cursor. Most rules have a tick labeled 'R' at this point.

Teach Yourself the Slide Rule - Section 06