I imagine what is going on is the answers on the multiple choice questions weren’t random and you were picking up on the pattern then retroconing a justification. Say for example

• A. 12
• B. 14
• C. 11
• D. 68

You threw out D right away because it was much different and argued that it had to be A or C because being off by one is an easy mistake. Now it’s just a question if even or odd, so you looked for a divide by 2. If found you went odd, if you found a multiple by 2 you went even.

Added to this you probably noticed a pattern. If C was the correct answer the next one was always A, etc.

If you aren’t convinced that its just really good test taking ability it would be pretty easy to use an AI and make it quiz you.