Skip to the question
MockTrackCreate a free account

Interactive product sample

Try the review loop in two minutes.

Choose an answer, check it, and—if you miss—use this sample's written hint before seeing the concise review. In your own practice, hints come from the optional AI tutor; without it you can show the answer and open the problem source.

  • No account
  • No AI
  • No answer data saved
The MockTrack loop
  1. 1 Answer
  2. 2 Guided retry
  3. 3 Review
Original MockTrack problemCounting · Medium
Five distinct notebooks are arranged in a row. The blue notebook and the green notebook may not be next to each other. How many arrangements are possible?

Choose one answer, then check it.