Question

what is the 31th term in the sequence 3, 6, 12, 24

Answer 1

There's many possible ways to solve it.
One way is to do it by finding the rule and repeat the rule all the way to the 31th term.
Or you can use the arithmetic sequence formula:
x = a + d(n-1)

a = The first term
d = The rule or common difference
n = Term position

If you need a walkthrough with the formula, then feel free to ask. ^_^