PCEP Practice Question: Data Types, Variables, Basic I/O and Operators
This PCEP practice question tests your understanding of data types, variables, basic i/o and operators. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A student writes the following code to calculate the average of two numbers:
```python
num1 = input("Enter first number: ")
num2 = input("Enter second number: ")
avg = (num1 + num2) / 2
print("Average:", avg)
```
When executed, the code raises a TypeError. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The input() function returns a string, not a number, so arithmetic operations are invalid without conversion
The `input()` function in Python always returns a string, regardless of what the user types. Attempting to use the `+` operator on two strings performs concatenation, not numeric addition, and then dividing a concatenated string by an integer with `/` raises a `TypeError` because the `/` operator is not defined for strings. To fix this, the inputs must be explicitly converted to numbers using `int()` or `float()` before arithmetic operations.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The division operator '/' is not allowed for integers
Why it's wrong here
Incorrect. '/' works with integers, returning a float.
✓
The input() function returns a string, not a number, so arithmetic operations are invalid without conversion
Why this is correct
Correct. input() returns a string; arithmetic requires numeric conversion.
Clue confirmation
The clue words "first", "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The addition operator '+' cannot be used with strings
Why it's wrong here
Incorrect. The '+' operator concatenates strings.
✗
The variable names num1 and num2 are reserved keywords
Why it's wrong here
Incorrect. 'num1' and 'num2' are not reserved keywords.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Python Institute often tests the misconception that `input()` returns a numeric type when the user types digits, leading candidates to overlook the need for explicit type conversion with `int()` or `float()`.
Trap categories for this question
Keyword trap
Incorrect. 'num1' and 'num2' are not reserved keywords.
Detailed technical explanation
How to think about this question
Under the hood, `input()` reads from stdin and returns a string object. When `+` is applied to two strings, Python invokes the `__add__` method for string concatenation, producing a new string. The `/` operator then attempts to call `__truediv__` on that string, which is not implemented, raising a `TypeError`. In real-world applications, failing to convert user input is a common source of bugs in data processing pipelines, where numeric inputs from forms or APIs must be explicitly cast before calculation.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Data Types, Variables, Basic I/O and Operators — This question tests Data Types, Variables, Basic I/O and Operators — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The input() function returns a string, not a number, so arithmetic operations are invalid without conversion — The `input()` function in Python always returns a string, regardless of what the user types. Attempting to use the `+` operator on two strings performs concatenation, not numeric addition, and then dividing a concatenated string by an integer with `/` raises a `TypeError` because the `/` operator is not defined for strings. To fix this, the inputs must be explicitly converted to numbers using `int()` or `float()` before arithmetic operations.
What should I do if I get this PCEP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first", "most likely". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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