\[\boxed{\mathbf{326}\mathbf{.}}\]
\[1)\ \frac{8 \cdot 5}{15 \cdot 16} = \frac{1 \cdot 1}{3 \cdot 2} = \frac{1}{6}\]
\[2)\ \frac{9 \cdot 13}{26 \cdot 3} = \frac{3 \cdot 1}{2 \cdot 1} = \frac{3}{2} = 1\frac{1}{2}\]
\[3)\ \frac{28 \cdot 36}{45 \cdot 49} = \frac{4 \cdot 4}{5 \cdot 7} = \frac{16}{35}\]
\[4)\ \frac{17 \cdot 8}{51 \cdot 44} = \frac{1 \cdot 2}{3 \cdot 11} = \frac{2}{33}\]