1. Calculate: $25 \times 13 \times 2 + 15 \times 13 \times 7=$
【Answer】2015

【Solution】
$$
\begin{array}{l}
25 \times 13 \times 2+15 \times 13 \times 7 \\
=5 \times 13 \times 10+5 \times 13 \times 21 \\
=5 \times 13 \times(10+21) \\
=5 \times 13 \times 31=2015
\end{array}
$$