SumRace blog

Guides, strategy and the maths behind the puzzles.

• SumRace Shop is open: the maths, now wearable — Twelve designs, all back-print hoodies and tees — magic squares, binary bands, Pascal’s triangle and the odd Gray code ring.
• Where the Tower of Hanoi actually gets used — Backup systems, brain assessments and rotary encoders all run on the same 2ⁿ − 1 logic as a stack of wooden disks.
• Tower of Hanoi: the puzzle that counts in binary — Why a perfect game always takes 2ⁿ − 1 moves, how the move counter picks your next disk, and the legend that runs for 585 billion years.
• Kakuro strategy: five techniques that solve most grids — From magic number combinations to cross-referencing runs — the core moves every Kakuro solver uses.
• Futoshiki for beginners: read the inequalities first — Why the < and > signs are the puzzle, not the grid — and how chains of inequalities hand you free digits.
• How to actually get faster at mental arithmetic — Speed comes from fewer steps, not faster steps. Three habits that cut solving time on any timed puzzle.