Dead Reckoning: Calculating Without InstrumentsThis volume describes techniques of computation and approximation that may be used to mentally and rapidly calculate mathematical quantities, including results of arithmetic operations and values of elementary functions. These methods range from very old to recent to brand new. They are not shortcuts, rather, the book is aimed at sharpening the mental skills needed to perform mathematical acrobatics. |
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Common terms and phrases
½ log A. C. Aitken a₁ accuracy accurate Aitken American Mathematical Monthly an+1 angle arccos arcsin arctan arrive b₁ casting out nines common logarithms consider continued fraction convenient cube root d₁ d₂ decimal places decimal point denominator derive divide divisibility tests earlier elevens test Equation 22 Error curve approximation Euclid's Algorithm example Fermat's method find log form 4k formula given number giving greatest common divisor Halley's method integer inverse large number last digit lightning calculators logarithms Mathematics Magazine melded memorized mental calculation mod 9 modular arithmetic multidigit number multiple Newton-Raphson method nines test number ending number of digits obtained original number perform prime factors prime number quotient R₁ range rational approximations recurring group remainder repeating group result sieve simplify single-digit square root step subtract Table techniques term three-digit tions triangular numbers trigonometric truncating two-digit endings two-digit numbers units digit