Answer: Python Puzzler #1731

The answer is C. The program prints:

56

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
47	yes	47
48	yes	48
18	no	48
56	yes	56
10	no	56

The code again

numbers = [47, 48, 18, 56, 10]
biggest = 0
for n in numbers:
    if n > biggest:
        biggest = n
print(biggest)