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  2. Mental calculation - Wikipedia

    en.wikipedia.org/wiki/Mental_calculation

    Mental calculation consists of arithmetical calculations using only the human brain, with no help from any supplies (such as pencil and paper) or devices such as a calculator. People may use mental calculation when computing tools are not available, when it is faster than other means of calculation (such as conventional educational institution ...

  3. Magic number (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Magic_number_(chemistry)

    The concept of magic numbers in the field of chemistry refers to a specific property (such as stability) for only certain representatives among a distribution of structures. It was first recognized by inspecting the intensity of mass-spectrometric signals of rare gas cluster ions. [ 1 ]

  4. Chisanbop - Wikipedia

    en.wikipedia.org/wiki/Chisanbop

    The Chisanbop system. When a finger is touching the table, it contributes its corresponding number to a total. Chisanbop or chisenbop (from Korean chi (ji) finger + sanpŏp (sanbeop) calculation [1] 지산법/指算法), sometimes called Fingermath, [2] is a finger counting method used to perform basic mathematical operations.

  5. Mental calculator - Wikipedia

    en.wikipedia.org/wiki/Mental_calculator

    A mental calculator or human calculator is a person with a prodigious ability in some area of mental calculation (such as adding, subtracting, multiplying or dividing large numbers). In 2005, a group of researchers led by Michael W. O'Boyle, an American psychologist previously working in Australia and now at Texas Tech University , has used MRI ...

  6. Portal:Chemistry/Textbook - Wikipedia

    en.wikipedia.org/wiki/Portal:Chemistry/Textbook

    absorption - adsorbent - adsorption - aeration - aerosol - alkali metal - alkaline earth - alkaline earth metal - allotrope - alloy - amalgam - analysis - atom - boiling - boiling point - chemical change - chemical element - chemical property - chromatography - colloid - column chromatography - compound - concentration - condensation - congener ...

  7. Mental abacus - Wikipedia

    en.wikipedia.org/wiki/Mental_abacus

    Mental calculation is said to improve mental capability, increases speed of response, memory power, and concentration power. Many veteran and prolific abacus users in China, Japan, South Korea, and others who use the abacus daily, naturally tend to not use the abacus any more, but perform calculations by visualizing the abacus.

  8. Turnover number - Wikipedia

    en.wikipedia.org/wiki/Turnover_number

    In chemistry, the term "turnover number" has two distinct meanings. In enzymology , the turnover number ( k cat ) is defined as the limiting number of chemical conversions of substrate molecules per second that a single active site will execute for a given enzyme concentration [ E T ] for enzymes with two or more active sites. [ 1 ]

  9. Complex number - Wikipedia

    en.wikipedia.org/wiki/Complex_number

    In mathematics, a complex number is an element of a number system that extends the real numbers with a specific element denoted i, called the imaginary unit and satisfying the equation =; every complex number can be expressed in the form +, where a and b are real numbers.