6. (3 points) A number, when it is reduced by 5 times, and then expanded by 20 times, the result is 40. What is this number?
【Solution】Solution: $40 \div 20 \times 5$
$$
\begin{array}{l}
=2 \times 5 \\
=10
\end{array}
$$

Therefore, the answer is: 10.