8. There is no less than 10 liters of milk in the bucket. How can you pour exactly 6 liters of milk from it using an empty nine-liter bucket and a five-liter bucket?
$\triangle$ Let's denote the initial amount of milk in the first bucket as $a$ liters. Let's think about how to use the fact that the number $a$ is not less than 10. The difference $a-10$ can be used, but the difference $a-11$ cannot. The solution is written as follows:

| Bucket with volume $a$ l | $a$ | $a-5$ | $a-5$ | $a-10$ | $a-10$ | $a-1$ | $a-1$ | $a-6$ | $a-6$ |
| :--- | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: | :---: |
| Bucket with volume 9 l | 0 | 0 | 5 | 5 | 9 | 0 | 1 | 1 | 6 |
| Bucket with volume 5 l | 0 | 5 | 0 | 5 | 1 | 1 | 0 | 5 | 0 |