$8 \cdot 85$ Write the 4 numbers $1,9,8,8$ in a row and perform the following operation: for each pair of adjacent numbers, subtract the left number from the right number, and write the difference between these two numbers, which counts as one operation. Then, perform the same operation on the row of 7 numbers thus obtained. Continue this process for a total of 100 operations. Find the sum of the final row of numbers.
[Solution] In each operation, the leftmost number in the row is only subtracted once, the rightmost number is only subtracted from once, and each number in the middle is both subtracted and subtracted from once. Therefore, after the operation, the sum of the numbers in the row increases by 7. After 100 operations, the sum of the numbers in the row is
$$
S=1+9+8+8+7 \times 100=726 .
$$