Missing Number: 6, 6, 7, ?, 91, 463

To find the missing number in the given sequence, let's analyze the pattern and characteristics of the sequence.

Observations:
- The sequence starts with two identical numbers, 6 and 6.
- The next number is 7.
- The fourth number is missing.
- The fifth number is 91.
- The sixth number is 463.

Pattern Analysis:
- The sequence starts with two identical numbers, which might be a coincidence or a pattern.
- The third number is simply the next consecutive number after the first two numbers.
- The fourth number is missing, so we need to figure out the pattern to determine the missing number.
- The fifth and sixth numbers seem unrelated to the initial sequence, so we should focus on the first three numbers.

Pattern Hypothesis:
Given the limited information, one possible pattern that fits the first three numbers is as follows:

- The first two numbers are the same: 6 and 6.
- The third number is the average of the first two numbers: (6 + 6) / 2 = 6.
- The fourth number is the next consecutive number after 7: 8.

Verification:
Let's check if this pattern holds true for the rest of the given sequence.

- The fifth number is 91, which does not fit the pattern we hypothesized.
- The sixth number is 463, which also does not fit the hypothesized pattern.

Conclusion:
Based on the observations, pattern analysis, and verification, we can conclude that the given sequence does not follow a consistent pattern. Therefore, it is not possible to determine the missing number with certainty.

Answer:
The missing number cannot be determined based on the given information.