A student says that if the denominator of a fraction in simplest form has a prime factor other than 2 and 5, its decimal expansion is non-terminating recurring. Which of the following fractions supports the student's statement?

Correct answer: \(\frac{11}{12}\)

For \(\frac{11}{12}\), the denominator is \(12=2^2\times3\). Since it contains the prime factor 3, its decimal expansion is non-terminating recurring: \(0.91\overline{6}\). In contrast, the denominators 8, 20 and 125 have only 2 and/or 5 as prime factors, so their decimal expansions terminate. Exam tip: First reduce a fraction to its simplest form, then check the prime factors of its denominator.