All Puzzles

A cycle-following strategy turns an almost impossible search into a surprisingly hopeful one.

How far can an army of pegs advance when every move must be a jump?

Two missing corners, thirty-one dominoes, and one coloring that settles everything.

One prize, three doors, and an informed host: should you switch?

Nine distinguished points of every triangle quietly share a single circle.

Adjacent angle trisectors of an arbitrary triangle form an equilateral triangle.

A seductive expected-value argument seems to say that switching is always better.

Find the greatest prime divisor by stripping factors from the remaining value.

Use the recurrence between consecutive even Fibonacci terms to skip every odd value.

Turn a finite scan into three arithmetic-series sums with inclusion–exclusion.