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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…
Public Math Postcards
Postcard from Public Math with thought provoking questions.
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…
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…
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.
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.
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?
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…
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…
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…
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
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…
I AM THE RHOMBUS
In one package: the strip of triangles and brochure for this new flexagon. The colorfully illustrated brochure will include folding directions, flexing directions, and images of the different possible faces.
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.…
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…
Puzzle Menu
A puzzle hunt hidden inside an 8-page pamphlet.
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.
G4G14 Exchange Gift (Martin Gardner Magic Trick)
We, on behalf of ThinkFun, would like to submit a physical gift based on a personal letter sent from Martin Gardner to one of our founders, Bill Ritchie, in 1994. We will submit photocopies of the letter, which describes how to perform the magic…
14-sided and Skew 8-sided Dice
A fair 14-sided die in the form of a heptagonal trapezohedron and a fair 8-sided die ("Skew d8") in the form of a triangular dihedron.
Octaroller
BUILD your OCTAROLLER ! from 3 parts square.
RACE your OCTAROLLER ! down the ramp in a straight line.
CHEER your OCTAROLLER ! with supplied cheering pom pom on a toothpick.
Octaroller is included in Geometric Foundations of Design: Old and New…
RACE your OCTAROLLER ! down the ramp in a straight line.
CHEER your OCTAROLLER ! with supplied cheering pom pom on a toothpick.
Octaroller is included in Geometric Foundations of Design: Old and New…
Veternary - Magic Trick
An animal based who-is-who in which with the right three questions any animal becomes uniquely identified using a ternary "sieve". For the first 16 animals this also works in binary.
Zebra Stripe Card
Zebra stripe IBM binary card.
A G4G14 Puzzle
This is a paper ring with a number puzzle. The hint is actually the logo that is at the beginning (which of course will be right after the end when it's a ring).
How to Put This Design on an Egg
I have made a full-color, two-sided instruction sheet on how to draw the attached design on an egg, along with a laminated picture of one of my eggs that has adhesive on the back to become a sticker.
The Martian Mayor Problem
The Martian Mayor Problem looks at designing square modular networks which create Euclidean distances between modules. The catch is that there are a limited number of tunnels (connections) between modules. This is a mostly open problem as far as I…