Answer: What Comes Next? #320

The answer is D: 27.

The rule

Add 3 each time.

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.

number = 9
for step in range(7):
    print(number)
    number = number + 3

When you run it, Python prints:

9
12
15
18
21
24
27