Ta có: \(M=\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right)...\left(1-\frac{1}{100}\right)\)
\(\Leftrightarrow M=\frac{1}{2}.\frac{2}{3}.....\frac{99}{100}\)
\(\Leftrightarrow M=\frac{1.2...99}{2.3...100}=\frac{\left(2.3.....99\right).1}{\left(2.3....99\right).100}=\frac{1}{100}\)