41. For a real number $x$, the symbol $[\mathrm{x}]$ represents the greatest integer not greater than $x$, for example $[0.3]=0,[\pi]=3,[-2.5]=-3$. If $\left[\frac{x+4}{10}\right]=5$, then the maximum value of $\left[\frac{6 x}{5}\right]$ is . $\qquad$
Answer: 67
Solution: According to the problem, we have
$$
\begin{array}{c}
5 \leq \frac{x+4}{10}<6 \\
46 \leq x<56 \\
\frac{276}{5} \leq \frac{6 x}{5}<\frac{336}{5} \\
55 \frac{1}{5} \leq \frac{6 x}{5}<67 \frac{1}{5}
\end{array}
$$

Solving, we get
Then
$$
\begin{array}{c}
5 \leq \frac{x+4}{10}<6, \\
46 \leq x<56, \\
\frac{276}{5} \leq \frac{6 x}{5}<\frac{336}{5}, \\
55 \frac{1}{5} \leq \frac{6 x}{5}<67 \frac{1}{5}
\end{array}
$$

Therefore, $\left[\frac{6 x}{5}\right]$ can be as large as 67.