A common fraction is a fraction in which numerator and denominator are both integers, as opposed to fractions. For example, is a common fraction, while
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is not. Common fractions are sometimes also called vulgar fractions (Derbyshire 2004, p. 171).
Complex Fraction, Fraction, Improper Fraction, Mixed Fraction, Reduced Fraction
Derbyshire, J. Prime Obsession: Bernhard Riemann and the Greatest Unsolved Problem in Mathematics. New York: Penguin, 2004.