Istoriia s uzelkami, ili Vse ne tak, kak kazhetsia - Kerroll L'iuis

Mathematics interested Charles Dodgson (Lewis Carroll) from the school bench. Where other children saw some dry numbers, he noticed a fascinating game. Thus, in "Stories with knots" in each nodules the author tried as discreetly as possible to weave one or more mathematical puzzles for entertainment and, perhaps, in the edification of readers.
Mathematician and writer Lewis Carroll is credited with several inventions: book cover, road chess, tricycle, electric pen, magonyic system for remembering names and dates. And no one is a tool for writing in the dark. Carroll himself invented the 16-square-metre card (a card with a grid of 16 square holes through which the invented symbols were drawn) and invented it himself - he used a system of dots and strokes with a mandatory point in the top left corner.
Not surprisingly, this invention belongs to Lewis Carroll: he suffered from insomnia. Trying to distract...