Answer: Python Puzzler #922

The answer is D. The program prints:

[4, 9]

Checked by running the program for real.

append adds one item to the end of the list each time round the loop. The loop runs for n = 2, 3.

A trace table follows the program step by step. Here’s this one:

n	n * n	results so far
2	4	[4]
3	9	[4, 9]

results = []
for n in range(2, 4):
    results.append(n * n)
print(results)

Try it: change one number in the program and predict the new output before you run it.