How Many Questions Can You Miss and Still Pass? Passing Score Math and Guessing
October 29, 2026
To find how many questions you must answer correctly, multiply the number of questions by the passing percentage and round up: needed = ⌈N × p⌉. The number you can miss is N − needed.
A 50-question exam with a 70% pass mark requires 35 correct answers, so you can miss 15. An 80-question exam at 75% requires 60 correct, so you can miss 20. A 100-question exam at 90% allows 10 misses.
Skip the math and get your answer instantly:
Open the Percentage Calculator →Table of Passing Scores
Rounding matters: for 25 questions at an 80% pass mark, you need 20 correct, with 5 misses allowed. For 45 questions at 70%, 45 × 0.7 = 31.5, so you need 32 correct and can miss 13. Exams with unscored pilot items may count fewer questions than are shown on the screen; check how the score is calculated, as some exams use scaled scores that depend on question difficulty rather than a raw percentage.
| Questions | Pass mark | Correct needed | Can miss |
|---|---|---|---|
| 25 | 80% | 20 | 5 |
| 45 | 70% | 32 (31.5 rounded up) | 13 |
| 50 | 70% | 35 | 15 |
| 80 | 75% | 60 | 20 |
| 100 | 90% | 90 | 10 |
Guessing and Negative Marking
On a four-option multiple-choice test, a blind guess is right 25% of the time, so guessing on all 50 questions yields an expected 12.5 correct (25%). The chance of guessing 35 or more right is far below one in a million, so guessing is not a path to passing. Where wrong answers are not penalized, you should answer every question. If there is negative marking, such as −1/3 point for a wrong answer on a 4-option question, a blind guess has expected value 0.25 × 1 − 0.75 × (1/3) = 0, so guessing is neutral on average; eliminating one option raises the odds to 1/3 and makes guessing worthwhile: 1/3 − (2/3)(1/3) = +0.11 points.
Using the Numbers to Study
Set a target above the minimum to leave a margin for nerves and ambiguity: if 70% is required, aim for 80+ on practice tests. Analyze misses by topic to find what yields the most gains. Work out the time per question: 90 minutes for 50 questions allows 1.8 minutes each; budget by marking hard items and returning. If you're close on a computer-adaptive test, the number of questions and their difficulty determine the outcome.
Caveats
Passing rules vary by exam: some require both an overall score and minimum scores in each section. Always check the official rules. This article describes the arithmetic.
Frequently Asked Questions
How do I find the number of correct answers needed?
Multiply the number of questions by the pass percentage and round up.
How many can I miss on 50 questions with a 70% pass mark?
15.
What is the expected score from guessing on a 4-option test?
25%.
Is guessing wise with negative marking?
It is neutral on average for blind guesses, and positive if you can eliminate options.
Do all exams use a simple percentage?
No, some use scaled scores or section minimums.