Answer: What Comes Next? #366

The answer is D: 41.

The rule

Add 3, then add 9, then 3, then 9, and so on. The pattern of adding takes turns.

The pattern as Python code

Here is a tiny Python program that follows the same rule. Type it into IDLE and run it to print the whole pattern, including the answer.

adds = [3, 9]
number = 5
for step in range(7):
    print(number)
    number = number + adds[step % 2]

When you run it, Python prints:

5
8
17
20
29
32
41