Ta có:
M=\(\frac{1}{2}.\frac{3}{4}.....\frac{99}{100}\)
M=\(\frac{1.3....99}{2.4....100}\)
Lại có:
N=\(\frac{2}{3}.\frac{4}{5}....\frac{100}{101}\)
N=\(\frac{2.4....100}{3.5....101}\)
\(\Rightarrow\)M.N=\(\frac{1.2.3......99.100}{2.3.4......100.101}\)
\(\Rightarrow\)M.N=\(\frac{1}{101}\)