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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). In addition to the logarithmic scales, some slide rules have other mathematical functions encoded on other auxiliary scales.
The calculator described above was called "Model No. 1" . [6] Model 2 had scales on the inner cylinder for calculating logs and sines.The "Fuller-Bakewell" model 3 had two scales of angles printed on the inner cylinder to calculate cosine² and sine ⋅ cosine [note 1] for use by engineers and surveyors for tacheometry calculations.
The rule of three [1] was a historical shorthand version for a particular form of cross-multiplication that could be taught to students by rote. It was considered the height of Colonial maths education [ 2 ] and still figures in the French national curriculum for secondary education, [ 3 ] and in the primary education curriculum of Spain.
Unit fractions can also be expressed using negative exponents, as in 2 −1, which represents 1/2, and 2 −2, which represents 1/(2 2) or 1/4. A dyadic fraction is a common fraction in which the denominator is a power of two , e.g. 1 / 8 = 1 / 2 3 .
Area of a cloth 4.5m × 2.5m = 11.25m 2; 4 1 / 2 × 2 1 / 2 = 11 1 / 4 Multiplication (often denoted by the cross symbol, ×, by the mid-line dot operator, ·, by juxtaposition, or, on computers, by an asterisk, *) is one of the four elementary mathematical operations of arithmetic, with the other ones being addition ...
In algebra, it is a notation to resolve ambiguity (for instance, "b times 2" may be written as b⋅2, to avoid being confused with a value called b 2). This notation is used wherever multiplication should be written explicitly, such as in " ab = a ⋅2 for b = 2 "; this usage is also seen in English-language texts.
The products of small numbers may be calculated by using the squares of integers; for example, to calculate 13 × 17, one can remark 15 is the mean of the two factors, and think of it as (15 − 2) × (15 + 2), i.e. 15 2 − 2 2.
A partially disassembled Curta calculator, showing the digit slides and the stepped drum behind them Curta Type I calculator, top view Curta Type I calculator, bottom view. The Curta is a hand-held mechanical calculator designed by Curt Herzstark. [1] It is known for its extremely compact design: a small cylinder that fits in the palm of the hand.