PCEP Practice Question: Data Types, Variables, Basic I/O and Operators
A programmer writes: x = 5; y = "10"; z = x + y. What will happen?
⚠ Common exam trap
Python Institute often tests the misconception that Python will automatically convert types to make the operation work, either by treating the integer as a string (concatenation) or the string as a number (addition), when in fact Python raises a TypeError 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
✓
TypeError: unsupported operand type(s) for +: 'int' and 'str'
Python does not implicitly convert between incompatible types for the '+' operator. When an integer (int) and a string (str) are used with '+', Python raises a TypeError, as it cannot decide whether to perform arithmetic addition or string concatenation without explicit conversion.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Prints error but continues execution
Why it's wrong here
The program stops unless the error is caught.
- ✗
Prints 510
Why it's wrong here
Would only happen if both were strings.
- ✓
TypeError: unsupported operand type(s) for +: 'int' and 'str'
Why this is correct
Correct; Python raises TypeError for mismatched types.
- ✗
Prints 15
Why it's wrong here
Would only happen if both were ints.
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