Six Math questions in the official ACT practice tests appear twice, copied word for word from an earlier numbered test into a later one. Every repeat lands in a cell the answer key marks Not Scored, so it never enters your raw score. Recognising one may save you time on that question, but it cannot earn you a point.

Here are the pairs we can reproduce, by Math question number:

In every pair the appearance in the lower-numbered test counts toward the score and the later one does not.

What a Not Scored cell is

The Math section presents 45 questions, but your raw score is out of 41. The other four are field test questions: ACT is trying them out for future forms and excludes them from scoring. The instruction sits in the answer key of both new tests:

Do not count correct answers for Not Scored cells, as those are for field test items not included in converting raw scores to scale scores.

So when you score a practice test, four of the 45 Math answers are set aside. Your Math raw score is a count of correct answers among the 41 scored questions, not a percentage of 45, and the conversion table expects a number with a maximum of 41. Counting all 45 gives you a figure that table was never built to read.

Do not memorise which numbers are skipped

The same page says something that matters more than the repeats:

the placement of these field test questions varies across different test forms, and will NOT remain in the same test item slots each test administration.

Question 29 being unscored in Practice Test 3 tells you nothing about question 29 on your test day, because the positions move between forms. Any advice built on specific question numbers has a shelf life of one test, and repeating it after that is worse than saying nothing.

Every unscored Math slot in Test 3 is a recycled question

This is the part worth knowing if you are planning which tests to sit.

Practice Test 3 has four unscored Math questions: 6, 18, 29 and 40. Every one of them appears in the table above: question 6 comes from Test 2, question 18 from Test 2, question 29 from Test 1, and question 40 from Test 1. All four had already been asked, and scored, on an earlier form.

That is one section of one form, so we are not calling it ACT's policy. In that section, though, the field test slots hold no new questions at all.

What this changes about using the four tests

Less than you might expect. Take Practice Tests 3 and 4 anyway: forty-one scored Math questions per form is still forty-one. We compared the Math sections only, so nothing here says anything about English, Reading or Science, in either direction.

Two adjustments are worth making. Score Math out of 41 rather than 45, setting the four Not Scored answers aside before you convert, or you are comparing a 45-question percentage against a scale built for 41.

Take Test 1 and Test 2 first if you are working through all four. Within the numbered set the repeats run from the lower numbers into the higher ones, so sitting Tests 1 and 2 first means you meet each of these questions in the slot where it counts. Going in the other order means six of your scored answers on Tests 1 and 2 are questions you have already seen.

How we checked this

We downloaded the four official practice test PDFs from act.org, extracted the Math sections, and compared every question in each form against every question in the others. Scoring status came from each form's own Mathematics Scoring Key, and we checked our reading of those keys against ACT's stated total: each key should show four unscored questions, because each says the raw score is out of 41, and each does.

Two further pairs look like repeats to the eye but our extraction could not separate genuine reuse from page-layout noise in those cases, so they are left out. Six is what we can reproduce, not a ceiling. One question per form defeats the extraction entirely, and we compared Math only, so the real figure across the whole battery may be higher.