In the following question, select the missing number from the given series.
3, 12, 24, 4, 16, 32, 5, 20, ?

The sequence can be broken down into triplets where a consistent multiplication pattern is applied to the first term of each triplet:
First triplet: (3, 12, 24)

3×4=12
3×8=24
Second triplet: (4, 16, 32)

4×4=16
4×8=32
Third triplet: (5, 20, ?)

5×4=20
5×8=40
Thus, the missing number is 40.