What is the value of $\square$ in $\frac{6400000}{400}=1.6 \times \square$?
For simplification $\frac{6400000}{400}=16000$, thus:

$$
\frac{6400000}{400}=1.6 \times \square \quad \Longrightarrow \quad 16000=1.6 \times
$$

It follows that $\square=10000$.