PCEP Practice Question: Data Types, Variables, Basic I/O and Operators
A beginner writes: x = '10'; y = 20; print(x + y). What happens?
⚠ Common exam trap
The trap here is that candidates often expect Python to behave like JavaScript or PHP, which implicitly coerce types, but Python strictly requires explicit type conversion for mixed-type operations.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Raises TypeError
Python's type system does not allow implicit concatenation of a string and an integer. The variable `x` is a string (`'10'`), and `y` is an integer (`20`). The `+` operator with these types triggers a `TypeError: unsupported operand type(s) for +: 'int' and 'str'` (or vice versa), as Python refuses to guess the programmer's intent.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Raises TypeError
Why this is correct
Python does not implicitly convert between str and int, so adding the string '10' to the integer 20 raises TypeError. This satisfies the question by identifying the runtime error produced when concatenation and addition are mixed across incompatible types.
- ✗
Prints 30
Why it's wrong here
Adding a str to an int raises TypeError, so nothing prints; Python never coerces '10' to 10 implicitly. It is tempting because arithmetic on numeric-looking strings feels natural, and int(x) + y would indeed print 30 after explicit conversion.
- ✗
Prints 10 + 20
Why it's wrong here
Not a string representation.
- ✗
Prints 1020
Why it's wrong here
TypeError is raised because '+' between str and int is undefined; concatenation requires both operands to be strings. It is tempting because '10' + '20' genuinely yields '1020', and str(y) would make that output correct here.
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Written by Johnson Ajibi, MSc IT Security
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This PCEP practice question is part of Courseiva's free Python Institute certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCEP exam.