9. Given $n$ positive integers (not necessarily distinct), their sum is 100, and the sum of any seven of them is less than 15. Then the minimum value of $n$ is $\qquad$ .
9. 50.

Let these $n$ numbers be $a_{1}, a_{2}, \cdots, a_{n}$. Then
$$
a_{1}+a_{2}+\cdots+a_{49} \leqslant 14 \times 7=98 \text {. }
$$

Thus $n \geqslant 50$, and when these 50 numbers are all 2, the condition is satisfied.