Answer: What Comes Next? #405

The answer is C: 41.

The rule

Add 1, then add 2, then add 3, then 4… The gap grows by one every 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 = 20
gap = 1
for step in range(7):
    print(number)
    number = number + gap
    gap = gap + 1

When you run it, Python prints:

20
21
23
26
30
35
41