This PCEP practice question tests your understanding of data types, variables, basic i/o and operators. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 developer runs the following code: x = 0.1; y = 0.2; print(x + y == 0.3). What is the output and why?
False, because the + operator is not defined for floats
Why wrong: The + operator works on floats.
True, because Python rounds to 0.3
Why wrong: Python does not round automatically; the result is 0.30000000000000004.
True, because Python uses decimal arithmetic
Why wrong: Python uses binary floating-point, not decimal.
False, due to floating-point precision
0.1+0.2 equals 0.30000000000000004, not exactly 0.3.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
False, due to floating-point precision
Option D is correct because floating-point numbers in Python (and most programming languages) are stored in binary (IEEE 754 double-precision), and values like 0.1 and 0.2 cannot be represented exactly. The sum 0.1 + 0.2 yields a result slightly greater than 0.3 (approximately 0.30000000000000004), so the equality comparison returns False.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
False, because the + operator is not defined for floats
Why it's wrong here
The + operator works on floats.
True, because Python rounds to 0.3
Why it's wrong here
Python does not round automatically; the result is 0.30000000000000004.
True, because Python uses decimal arithmetic
Why it's wrong here
Python uses binary floating-point, not decimal.
False, due to floating-point precision
Why this is correct
0.1+0.2 equals 0.30000000000000004, not exactly 0.3.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Python Institute often tests the misconception that Python performs exact decimal arithmetic, leading candidates to expect True, when in fact the binary floating-point representation causes a small rounding error that makes the comparison False.
Detailed technical explanation
Under the hood, Python floats are 64-bit IEEE 754 doubles, which allocate 1 sign bit, 11 exponent bits, and 52 mantissa bits. The value 0.1 in binary is a repeating fraction (0.0001100110011...), so it is approximated. This precision issue is not a bug but a fundamental property of binary floating-point representation, and it can cause subtle bugs in financial calculations or comparisons where exact equality is expected.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the PCEP exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
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..
The correct answer is: False, due to floating-point precision — Option D is correct because floating-point numbers in Python (and most programming languages) are stored in binary (IEEE 754 double-precision), and values like 0.1 and 0.2 cannot be represented exactly. The sum 0.1 + 0.2 yields a result slightly greater than 0.3 (approximately 0.30000000000000004), so the equality comparison returns False.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
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.
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