Is the Tower of Hanoi Test a diagnostic tool for cognitive impairment?

No. It is a casual self-assessment and practice game, not a medical diagnosis.

Why is the optimal move count 15 for four discs?

The optimal solution follows the formula 2^n - 1, where n is the number of discs; for four discs that equals 15.

Can I improve my score by practicing?

Yes, repeated practice helps you internalize the recursive pattern and reduce unnecessary moves.

Does the test record how long I take?

No, this version only counts moves; there is no timer.

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Tower of Hanoi Test

A stack of four discs sits on the left rod. Move the whole tower to the right rod, one disc at a time, never placing a larger disc on a smaller one. The fewer moves beyond the optimal 15 and the less time it takes, the better your planning score.

Press Start, then tap a rod to pick a disc up and another rod to drop it.

About the Tower of Hanoi

The Tower of Hanoi is a classic puzzle invented in 1883 and used ever since to measure executive function and planning. A recursive solution moves a tower of n discs in exactly 2^n − 1 steps, so four discs can never be finished in fewer than 15 moves. Reaching 15 is easy to miss by one careless extra move.

Tap one rod to pick up its top disc, then tap another to drop it. A move is refused if it would put a larger disc on a smaller one, and the timer only starts on your first accepted move. Your grade weighs how close your move count is to the optimum together with how long the puzzle took.

Plan your path in trail making · or stretch your working memory with mental math

About

The Tower of Hanoi Test measures planning ability, working memory, and sequential problem solving by asking you to move a stack of four discs from the left rod to the right rod. Only one disc may be moved at a time, and a larger disc can never be placed on top of a smaller one. The puzzle requires you to hold intermediate goals in mind while executing a precise sequence of moves.

In this version the optimal solution takes 15 moves. The game tracks each move you make and stops when the tower is correctly rebuilt on the target rod. Because the rules are simple but the solution space grows exponentially, the task reveals how well you can organize multi-step actions under constraint.

How your result is scored

Your result is the total number of moves you used to complete the transfer. Fewer moves indicate more efficient planning; the minimum possible is 15. The test does not impose a time limit, so the score reflects pure move efficiency rather than speed.

A score of 15 means you found the optimal solution. Scores between 16 and 25 suggest you understood the strategy but made a few redundant moves. Higher counts usually mean the sequence was not fully planned ahead or the rules were momentarily forgotten. Because this is a casual self-assessment, treat the number as a rough indicator of planning fluency, not a clinical measure.

Tips to improve

Visualize the final stack and work backward to identify the first necessary move.
Always move the smallest disc every other turn to maintain the alternating pattern.
Keep the largest disc stationary until all smaller discs are cleared from its path.
If you get stuck, reset and rehearse the first five moves from memory.
Practice with three discs first to internalize the recursive pattern before attempting four.

Frequently asked questions

Is the Tower of Hanoi Test a diagnostic tool for cognitive impairment?: No. It is a casual self-assessment and practice game, not a medical diagnosis.
Why is the optimal move count 15 for four discs?: The optimal solution follows the formula 2^n - 1, where n is the number of discs; for four discs that equals 15.
Can I improve my score by practicing?: Yes, repeated practice helps you internalize the recursive pattern and reduce unnecessary moves.
Does the test record how long I take?: No, this version only counts moves; there is no timer.