To solve this question, let's look for a pattern in the given sequence: 6, 396, 2376, 1425.6, 8.5536, ?.
If we observe carefully, we can see that each number in the sequence is obtained by multiplying the previous number by 66. So, let's continue this pattern:
6 * 66 = 396
396 * 66 = 2376
2376 * 66 = 156816
156816 * 66 = 10357656.96
10357656.96 * 66 = 682682448.96
Therefore, the missing number in the sequence is 682682448.96.
Now let's look at the options given:
A. .00513216
B. .0513216
C. .513216
D. 5.13216
None of the options match the missing number 682682448.96. So, none of the given options are correct.
Hence, the given question may have been misprinted or there may be an error, as the correct answer is not listed among the options provided.