10. (10 points) When the fraction $\frac{1}{2016}$ is converted to a repeating decimal, the repeating block has exactly $\qquad$ digits.
【Answer】Solution: $\frac{1}{2016}=1 \div 2016=0.00049603174603174 \cdots$, so, the repeating part is 603174, the repeating part has exactly 6 digits. Therefore, the answer is: 6.