Logic error

Term

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Definition

The program runs but gives the wrong result because the algorithm is wrong, for example using > instead of >=. 2025 markers said students confused these with syntax errors.

Example: Average = total / 2 instead of total / count.

Found in: 2025 HSC marking guidelines, school notes, past SDD papers.

Where you'll use it in the test

Syllabus area: Y11 Programming Fundamentals.

Question types it can appear in

Multiple choice: Pick the option that matches the definition or example.
Fill in the blanks: Choose this term to complete a statement or table.
Short answer: Outline how a debugging tool finds logic errors
Code reading: Code or algorithm reading: interpret a fragment and state its output or purpose.

Where it has appeared in the paper

The Software Engineering Project (Part A). Part letters follow each paper’s own layout.

How to use it

A model sentence

General advice, built from the definition and example above

“The program runs but gives the wrong result because the algorithm is wrong, for example using > instead of >=.” Then apply it: Average = total / 2 instead of total / count.

In a short answer, give the definition in your own words first, then tie it to the situation in the question. Do not copy the example above unless it fits the scenario.

Command words used with it

From the linked past questions

Outline: Sketch in general terms; indicate the main features of. (2025 HSC Q15b (3 marks): Testing and debugging)

Go deeper

Flashcard: Logic error in Programming Fundamentals (Year 11) · study that set
Memorise: Testing and code quality (Year 11)
Notes: Debugging tools and error types (The Software Engineering Project (Year 12))
Notes: Errors (Year 11 content (Programming fundamentals, OOP, Mechatronics))
Master answer: sdd2022-q28 (6 marks, short answer / extended) (Master model answers: The Software Engineering Project (written answers))
Master answer: hsc2025-q15b (3 marks, short answer) (Master model answers: The Software Engineering Project (written answers))
Full term page: every question, note and marking comment for Logic error

Check yourself

Explain “Logic error” in one sentence, give an example, and name a question type that could test it.

Reveal the answer

The program runs but gives the wrong result because the algorithm is wrong, for example using > instead of >=. 2025 markers said students confused these with syntax errors.

Example: Average = total / 2 instead of total / count.

Could be tested as: Multiple choice, Fill in the blanks, Short answer, Code reading.

Quick multiple choice

Which of these is a LOGIC error?

Dividing by zero when the user enters 0
Forgetting a colon after if in Python
Misspelling print as pritn
A program that calculates an average by dividing by 10 instead of the count of numbers

Show the answer

Logic errors run but give wrong results. Syntax errors stop the code compiling/running; runtime errors crash during execution (e.g. divide by zero).

Source: original (written for this study pack; not a NESA question). Open it in the multiple-choice bank.