Maker's Name: 
Concise, Japan
80 × 80 × 5 mm

Inexpensive plastic circular slide rule.

Circular slide rules date back to William Oughtred in the 1620s, but were less common than linear ones in the twentieth century. They have the advantage that one does not 'run off the end of the scale' but on the other hand it can be more difficult to keep track of the decimal point in extended calculations. The back of the 'rule' carries a table of commonly used conversion factors.

This item is part of the UQ Physics Museum Good Old days of Calculation Tour
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