Nice idea! I like how the robot goes from friendly to crazy, and end up feeling like a lab rat for testing. Havin the timer really makes the questions stressful, and it's good that making an error only throws you back one door.
The puzzles get too complicated too fast, however. It's like there is no in between from an easy no brainer, to a puzzle that requires more math and head scratching. The difficult math problem isn't that hard, I think it's mostly the font which confuses you. A few puzzles to lengthen the game would work wonders. It would also give the robots descent into madness more of a substance, as it would be happening over time. I would also give more time to the player for some puzzles. 10 seconds for that hard math question is too little imo for example.
The idea is great and I enjoyed it!