Tính nhanh: \(\left( {1 - \frac{1}{4}} \right) \times \left( {1 - \frac{1}{5}} \right) \times \left( {1 - \frac{1}{6}} \right)\, \times \left( {1 - \frac{1}{7}} \right) \times \left( {1 - \frac{1}{8}} \right)\).

\(\left( {1 - \frac{1}{4}} \right) \times \left( {1 - \frac{1}{5}} \right) \times \left( {1 - \frac{1}{6}} \right)\, \times \left( {1 - \frac{1}{7}} \right) \times \left( {1 - \frac{1}{8}} \right)\)

\( = \frac{3}{4} \times \frac{4}{5} \times \frac{5}{6} \times \frac{6}{7} \times \frac{7}{8}\)

\( = \frac{{3 \times 4 \times 5 \times 6 \times 7}}{{4 \times 5 \times 6 \times 7 \times 8}} = \frac{3}{8}\).