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How to Use a Pickett Slide Rule

A slide rule is a mechanical calculator that pre-dates modern electronic calculators. The accuracy of a slide rule depends on the length of the rule. Most pocket sized slide rules, like many Pickett brand slide rules, are accurate to 3 or 4 significant figures. To perform calculations on a slide rule, it is important to understand that decimal calculations are something that you would do either in your head or on a separate sheet of paper. For calculating purposes, 0.00452 is the same as .452 or 452. Each of those numbers has 3 significant figures. The only difference is the placement of the decimal.

Things You'll Need

Pickett slide rule

Instructions

Multiplication and Division
- 1
  Set one of the two multiplication factors over the other factor by sliding the center of the rule out. For example, to multiply by 2, slide the start of the C scale to the 2 on the D scale. To multiply by 3, slide the end of the C scale to the 3 on the D scale.
- 2
  Slide the hairline to the location on the scale of the two factors that you would like to multiply.
- 3
  Read the lower number as your answer. For example, slide the hairline to 2 to read the answer for 2 x 2 as 4. Slide the hairline to 4.5 to read the answer of 4.5 x 2 as 9.
- 4
  Reverse the way you read the answer to use your slide rule for division. For division, use the D scale as your source scale and the C scale for your result.
Square Root Calculations
- 5
  Move the hairline to the number on the D scale for which you would like to calculate the square root.
- 6
  Read the two numbers on the A and B scale to find the square root of the number on the D scale.
- 7
  Use the left hand A and B scale for numbers with an odd number of digits. Use the right hand A and B scale for numbers with an even number of digits. Pickett slide rules have two complete scales that calculate based on the number of digits in the number.

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