Thank you for taking part in this study. You will complete two mental arithmetic tasks:
Each task starts with a short 30-second practice, followed by a 2-minute main trial.
Use the number keys to type your answer, then press ENTER to submit. Press BACKSPACE to correct a typo.
The screen shows one number at a time — it updates to your last answer after each submission. Calculate the next value in your head. If you make a mistake, keep going from where you are.
Thank you — you have finished both tasks! Your data will now download as a CSV file.