Python Puzzler #177

Python Puzzler 177 card

Challenge type: Python Puzzlers  ·  Difficulty: ★☆☆☆☆ Easy peasy  ·  Topic: strings

Read this Python program carefully. Don’t run it yet! Can you work out exactly what it prints?

Python puzzler 177 code
What does it print?
word = "robot"
print((word + " ") * 4)

Choose an answer

ChoiceOutput
A
robot robot robot robot 
B
robot 4
C
robot robot robot robot robot 
D
robotrobotrobot   
Need a hint?

Pretend you are the computer. Go through the program one line at a time, and write down every variable’s value on paper as it changes. Programmers call this a trace.

Grown-ups: Reading code and predicting what it does is a key programming skill. Once your child has chosen an answer, run the code in IDLE together to check.

For teachers and grown-ups

Skills practised: Code reading, tracing variables, and understanding Python syntax.

The big idea: Predicting a program's output before running it builds a solid mental model of how code works.

Questions to ask:

  • What is the value of each variable after every line?
  • Which line decides the output?
  • What small change would make it print something different?

Take it further: Children use a trace table on paper for the code, then run it in IDLE to check, and change one value to make a new puzzle for a friend.