Example 7. Calculate:
$$
\frac{(742-108+321 \times 0.082) \times(37.2-28.7)}{517.4 \times(90.28-37.2)}
$$
$$
\begin{array}{l}
\frac{(742-108+321 \times 0.082) \times(37.2-28.7)}{517.4 \times(90.28-37.2)} \\
\approx \frac{(634+26.3) \times 8.5}{517 \times 53.1} \approx \frac{660 \times 8.5}{517 \times 53.1} \\
\approx \frac{5610}{27500} \approx 0.20
\end{array}
$$