Answer: Python Puzzler #3919

The answer is A. The program prints:

56

This answer was checked by running the program for real.

Why?

The loop remembers the biggest number it has seen so far, and replaces it whenever it finds a bigger one. This is how computers find the maximum.

Trace table

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

n	n > biggest?	biggest
7	yes	7
56	yes	56
14	no	56
21	no	56
12	no	56

The code again

numbers = [7, 56, 14, 21, 12]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)