Yes, this is a mind reading stampy How to use: Click the green flag. Then, choose a number from 10 to 99. Whatever number you want! Next, add the digits from your number together. Subtract the total from the original number. Lastly, remember the letter next to your final number. Then click the stampy! For example: Let's say you picked 83. 8 + 3 = 11. Then you would do 83 - 11. That's 72. You would remember the letter next to 72 and click the cookie.
Credit to @PullJosh for making the system.