Understanding Multiplication on the Versalog 1460
Multiplication is one of the fundamental calculations performed on the Post Versalog 1460. The calculation uses the relationship between the logarithmic C and D scales.
A slide rule does not multiply numbers directly. Instead, it adds logarithmic distances. The result is obtained by aligning values and reading the combined relationship.
The C and D Scale Relationship
The D scale is the primary fixed reference scale. The C scale is the movable scale used with the D scale for multiplication.
- D scale: fixed reference.
- C scale: movable multiplication scale.
- Cursor: transfers and reads the result.
Basic Multiplication Procedure
To multiply two numbers using the C and D scales:
- Place the first number of the calculation on the C scale.
- Align that value with the second number on the D scale.
- Move the cursor to the second value on the C scale.
- Read the answer from the D scale.
- Determine the decimal position using estimation.
Example: Multiplying 2 × 3
To calculate 2 × 3:
- Set the 1 index of the C scale over 2 on the D scale.
- Locate 3 on the C scale.
- Read the result on the D scale.
- The answer is approximately 6.
The slide rule gives the position of the result. The user determines the decimal placement by understanding that 2 × 3 must be close to 6.
Using the Cursor
The cursor allows the operator to transfer values accurately between scales. The hairline should be aligned carefully with the selected value before reading the result.
- Keep the cursor square to the slide rule.
- Align the hairline precisely.
- Avoid reading values from the edge of the cursor.
Calculations Beyond the First Range
The C scale has a range from 1 to 10. Some multiplication results require using the second section of the scale.
When the calculation exceeds the end of the scale, use the alternate index and continue the calculation from the beginning of the scale.
Estimation and Decimal Placement
The slide rule provides significant figures but does not provide decimal points. The operator must estimate the expected magnitude before accepting the answer.
- 2 × 3 is approximately 6.
- 20 × 30 is approximately 600.
- 200 × 300 is approximately 60,000.
Multiplication Using CI
The Post Versalog 1460 also supports efficient multiplication and division techniques using the CI scale.
The CI method becomes especially useful when calculations contain several multiplication and division operations.
See Versalog 1460 CI Scale Method for advanced techniques.
Common Mistakes
- Using the wrong scale.
- Reading the C scale instead of the D scale for the answer.
- Forgetting decimal estimation.
- Misaligning the cursor hairline.
Recommended Diagrams
- C and D scale multiplication alignment.
- Cursor reading example.
- Calculation crossing the scale index.
- Decimal estimation example.
Continue Learning
Continue to Versalog 1460 Division.