# Browse Items (67 total)

- Tags: G4G14

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## Quadratic Formula Nomograph

This is a cute graphical computing device which finds the roots of a quadratic polynomial. Stretch the (included) string between two scales representing the coefficients of the polynomial, and it tells you the roots! This device is based on an…

**Tags:**
G4G14, Recreational Math

## 4!-Fold Puzzle

Are there any polycubes that can be unfolded into exactly a rectangle? This problem was solved in 2019. The smallest solution forms a nice puzzle — fold the rectangle into a polycube!

**Tags:**
G4G14, polycube, polyominoes, Puzzle

## C.L. Dodgson (Lewis Carroll) Oxford Mathematician

Lewis Carroll, the nom de plume of the Rev. Charles L. Dodgson, a mathematics lecturer at Oxford, was also an innovator in recreational mathematics, magic, puzzles, cryptography, and inventions. His appearances in Scientific American began with…

**Tags:**
G4G14, Recreational Math, Word Play

## 14 Rabbiducks

The puzzle is to fit 14 “rabbiduck” polyomino pieces into an 8x11 rectangle. (Gardner wrote about polyominoes in multiple columns. The specific polyomino pieces used are inspired by the rabbit/duck illusion that Gardner called the Rabbitduck in his…

**Tags:**
G4G14, Puzzle, Recreational Math

## The Art of Destroying Flexagons

Destroying flexagons can be fun and artistic! We suggest 4 different ways to artistically destroy flexagons, each with its own merit. Our exchange gift is a set of 4 flexagons strips, one for each demonstration and the attached explanation sheet.

**Tags:**
G4G14, Puzzle, Recreational Math, Toy

## Rep-Tile Tangram

The gift will be a number of cut-out pages to create a rep-tile tangram: A tangram shape that is made from tangram shapes, that are made from tangram shapes.

**Tags:**
G4G14, Puzzle, Recreational Math

## Traveling Through the Sierpinski Carpet and Menger Sponge

An ant wants to travel from one corner of the Sierpinski carpet to the opposite corner using the shortest possible route. And his friend, a termite, wants to do the same in the Menger sponge. Can you guide them well?

**Tags:**
G4G14, Puzzle, Recreational Math

## A "Pick a Card" Card

A card (roughly the size of an index card) with an image that contains 54 playing cards (some duplicates, of course!). A spectator chooses one of the playing cards and, after a few questions, the magician reveals the choice!

The premise is similar…

The premise is similar…

**Tags:**
G4G14, Magic, Recreational Math

## Penrose P3

I am making paper flexagons with Penrose patterns on them to illustrate the patterns. My stuff touches three things from Martin Gardner, Flexagons, Penrose Tiles, and Polyominos (the classification system for tetraflexagons is based on these with a…

**Tags:**
Art, G4G14, Puzzle, Recreational Math

## Abstract Photograph - Acura TL

One of my interests is abstract photography, using ordinary photographs as the “paint” and using spatial and mathematical transformations to create an image from one or more sources. One transformation that I’ve been exploring is “Inside Out”, which…

**Tags:**
Art, G4G14, photography, Recreational Math

## The Accountant

Martin Gardner would sometimes wrap puzzles inside stories he concocted, such as with the book “The Numerology of Dr. Matrix.” The following puts my favorite puzzle in that tradition: The Accountant

by Barney Sperlin

by Barney Sperlin

**Tags:**
G4G14, Legacy, Recreational Math

## A Torus Without Diagonals

Cut-and-fold a polyhedron with 7 vertices, 14 faces, 21 edges, and a hole through it like a doughnut. A cube has internal diagonals that connect the diametrically opposite corners. By contrast, this polyhedron has no internal diagonals. There are…

**Tags:**
G4G14, Puzzle, Recreational Math

## StarHex-14: Theo Geerinck's 14 Polystars

14 tiles consisting of hexagons with 0 to 6 equilateral triangles attached on their edges can be cut from card stock provided to solve the large collection of puzzle figures presented. Five colors, each tile shape is unique with one mirror pair.…

**Tags:**
G4G14, Puzzle, Recreational Math

## The 14 Two-Color Frieze Symmetries in Mosaic Knitting

Mosaic knitting, a relatively new form of two-color knitting, has become popular because it is easier for the knitter than most traditional forms of color work. The price of this ease is an unusual set of restrictions on color placement for the…

**Tags:**
Art, G4G14, Recreational Math

## Golomb Rulers

A perfect ruler for daily use. In mathematics, a Golomb ruler is a set of marks at integer positions along a ruler such that no two pairs of marks are the same distance apart.

**Tags:**
G4G14, Recreational Math

## Flippe Top

This document describes how I designed a new kind of top, which flips not just once, but over and over. I call it a "flippe top". It can be made either from wood or by 3D printing.

**Tags:**
3D printed, G4G14, Toy