Answer: Python Puzzler #3938

The answer is D. The program prints:

52

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:

nn > biggest?biggest
47yes47
5no47
52yes52
50no52
38no52

The code again

numbers = [47, 5, 52, 50, 38]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)

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