9. (16 points) There are six piles of apples, and their numbers form an arithmetic sequence. Junjun picks one of the piles and takes out 150 apples, distributing them to the other 5 piles, giving 10, 20, 30, 40, and 50 apples to each pile in sequence. After the distribution, Junjun finds that the number of apples in these 5 piles is exactly 2 times, 3 times, 4 times, 5 times, and 6 times the number of apples in the pile he picked. How many apples are there in total in the six piles? $\qquad$
【Solution】Solution: Let the later portions be: $a, 2a, 3a, 4a, 5a, 6a$. Then their original values were $a+150, 2a-10, 3a-20, 4a-30, 5a-40, 6a-50$. According to the subsequent numbers, the common difference is $5a-40-(4a-30)=a-10$. Based on the common difference, the value before $2a-10$ should be $a-20$. Therefore, $a+150$ is the maximum value of the sequence. $a+150-(a-10)=160$. So, $6a-50=160$. Therefore, $a=35$. Hence, the later quantities are $35, 70, 105, 140, 175, 210$. The total is $35+70+105+140+175+210=735$ (units). Therefore, the answer is: 735