Your question is Explaining a Simple Math Mistake. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Tell me about a time you made or caught a simple quantitative mistake in your own work, like an algebra, logic, or spreadsheet error. How did you communicate it, fix it, and make sure it didn’t happen again?