3. (8 points) Xiaopang used all of this month's salary to buy a stock. On the first day, the stock price increased by $\frac{1}{10}$, on the second day it decreased by $\frac{1}{11}$, on the third day it increased by $\frac{1}{12}$, and on the fourth day it decreased by $\frac{1}{13}$. At this point, the value of his stock is exactly 5000 yuan. What was Xiaopang's salary this month? $\qquad$ yuan.
【Solution】Solve: $5000 \div\left(1-\frac{1}{13}\right) \div\left(1+\frac{1}{12}\right) \div\left(1-\frac{1}{11}\right) \div\left(1+\frac{1}{10}\right)$
$$
\begin{array}{l}
=5000 \times \frac{13}{12} \times \frac{12}{13} \times \frac{11}{10} \times \frac{10}{11} \\
=5000(\text { yuan })
\end{array}
$$

Answer: Xiao Pang's salary this month is 5000 yuan.
Therefore, the answer is: 5000.