Curiosa mathematica, part II : Pillow-problems thought out during wakeful hours

A charming assortment of seventy‑two mathematical riddles awaits anyone who enjoys turning idle moments into mental gymnastics. The problems span arithmetic tricks, clever algebraic twists, and elegant geometric challenges, each presented with concise diagrams that make the reasoning visible at a glance. The author’s informal commentary reveals how these “pillow‑problems” were devised during quiet, wakeful hours, offering a glimpse into the gentle curiosity that fuels the work.

The solutions are deliberately crafted to be followed in the mind, encouraging listeners to trace each step without needing pen or paper. Along the way, brief historical notes and playful notations add flavor, while the careful layout prevents the frustration of hunting back and forth through pages. Whether you’re a seasoned puzzler or just looking for a stimulating mental diversion, this collection invites you to engage with mathematics in a relaxed, conversational style.