I2.3 If $\log _{10} 210+\log _{10} k-\log _{10} 56+\log _{10} 40-\log _{10} 120+\log _{10} 25=p$, find $p$
$\begin{aligned} p & =\log _{10} \frac{210 \times 32 \times 40 \times 25}{56 \times 120} \\ & =\log _{10}(10 \times 4 \times 25) \\ & =3\end{aligned}$