Tower of Hanoi
Move all discs to the right peg
About this trainer
The Tower of Hanoi is a puzzle with three pegs and a stack of different-sized disks. Your job is to move the whole stack from the first peg to the last, one disk at a time, never placing a larger disk on top of a smaller one.
What it develops
It trains planning ahead and goal-directed thinking: you have to hold the end state in mind and work out a sequence of sub-moves to reach it. Psychologists use it as a classic measure of executive function and frontal-lobe planning.
History
Lucas sold it commercially in 1883 wrapped in a fake legend about a temple where priests move 64 golden disks, and the world supposedly ends when they finish. The puzzle spread quickly as a parlour game and later became a standard tool in mathematics, computer science, and neuropsychology.
Who created it — and when
It was invented by the French mathematician Edouard Lucas in 1883, who first sold it under the pen name "N. Claus (de Siam)" - an anagram of "Lucas d'Amiens", his home town.
How to train
Think recursively: to move a stack of N disks, first move the top N-1 onto the spare peg, shift the biggest disk across, then move the N-1 back on top. Plan a few moves ahead rather than grabbing the nearest legal move, and for an odd number of disks start by sending the smallest disk toward the target peg, alternating its direction each turn.
How long to practise
Short, focused sessions of 10 to 15 minutes work best, a few times a week. Once you can solve a given height optimally, add a disk rather than repeating the same easy size.
Evidence base
The evidence is strongest for exactly what you would expect: you get faster and more accurate at the puzzle itself and at closely related planning tasks, and it remains a respected clinical measure of planning ability. Broad claims that it lifts general intelligence or everyday problem-solving are far weaker - reviews of brain training repeatedly find little reliable far transfer, so treat the grand promises with caution.
Recommendations
After each solve, replay it in your head and ask whether a shorter path existed - reflection on your own moves trains the planning more than blind repetition.
FAQ
Is there always a best solution?
Yes. For any number of disks there is a single shortest solution, and it takes 2 to the power N minus 1 moves - 7 moves for 3 disks, 1023 for 10.
Will it make me smarter overall?
Honestly, probably not in a broad sense. You will get clearly better at this puzzle and similar planning tasks, but evidence that it boosts general intelligence or unrelated everyday skills is weak.
Why do I keep getting stuck near the end?
Usually because you moved without a plan. Try working backward from the goal and think in terms of moving whole sub-stacks, not single disks - that is the recursive trick that makes it click.
Variants
Common variations change the disk count (the minimum number of moves is always 2 to the power N, minus 1), add a fourth peg (the Reve's puzzle), or impose extra rules such as only moving disks between adjacent pegs. Related planning puzzles include the Tower of London, which is widely used in cognitive testing.