Mathematics I / Rational and Irrational Numbers
Practice question · Numerical answer

Write 84/126 in lowest terms. What is the numerator of the reduced fraction?

Hints
  1. Divide both numbers by their gcd, that is exactly what 'lowest terms' means.
  2. gcd(84, 126) = 42.
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2

Why

gcd(84, 126) = 42, and 84/42 = 2 while 126/42 = 3, so the fraction is 2/3 and the numerator is 2. Dividing by anything smaller than the gcd leaves the fraction reducible; the lowest-terms form is the unique one with coprime numerator and denominator.

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