Answer: Python Puzzler #3400

The answer is A. The program prints:

55

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
51	yes	51
13	no	51
22	no	51
55	yes	55
31	no	55

The code again

numbers = [51, 13, 22, 55, 31]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)