[amp_mcq option1=”3″ option2=”1″ option3=”4″ option4=”8″ correct=”option1″]
The answer is $\boxed{4}$.
The missing number is the number that completes the sequence:
$1, 2, 4, 8, 16, 32, \boxed{64}$
This is a geometric sequence with a common ratio of $2$. In other words, each term is $2$ times the term before it.
Therefore, the missing number is $2^6 = \boxed{64}$.