Answer:
Most likely answers are either 6 or 8.
Step-by-step explanation:
The sequence could be of all even numbers, so 2, 4, 6, 8, etc.
Or of all powers of 2, starting at 2, so 2, 4, 8, 16, etc.
Since there are an infinite number of sequences that fit the pattern, you just have to choose the most likely.
