Slide rule
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A slide rule is a hand-operated mechanical calculator consisting of slidable rulers for conducting mathematical operations such as multiplication, division, exponents, roots, logarithms, and trigonome
Typical ten-inch (25 cm) student slide rule (Pickett N902-T simplex trig)
Cursor on a slide rule
This slide rule is positioned to yield several values: From C scale to D scale (multiply by 2), from D scale to C scale (divide by 2), A and B scales (multiply and divide by 4), A and D scales (squares and square roots).
A normal-sized slide rule sitting inside a 7-foot (2.1 m) teaching model
Logarithm
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In mathematics, the logarithm of a number is the exponent by which another fixed value, the base, must be raised to produce that number. For example, the logarithm of 1000 to base 10 is 3, because 100
Slide rule
…hand-operated mechanical calculator consisting of slidable rulers for conducting mathematical operations such as multiplication, division, exponents, roots, logarithms, and trigonometry. It is one of the simplest analog computers. Slide rules exist in a diverse range of styles and generally appear in a linear, circular…
The logarithm keys (LOG for base 10 and LN for base e) on a TI-83 Plus graphing calculator
A nautilus shell displaying a logarithmic spiral