The Second Book of Mathematical Puzzles and Diversions

Tetraflexagons 27
c d
FIG. 9.
How to make a tetra-tetraflexagon.
making tetraflexagons of this sort, but adding one or more
additional rows (which does not change the essential struc-
ture) makes the model easier to manipulate.
The tetra-tetraflexagon shown in Figure 9 has often been
used as an advertising novelty because the difficulty of find-
ing its fourth face makes it a pleasant puzzle. I have seen
many such folders, some dating back to the 1930's. One had
a penny glued to the hidden face; the object of the puzzle
was to find the lucky penny. In 1946 Roger Montandon, of
The Montandon Magic Company, Tulsa, Oklahoma, copy-
righted a tetra-tetraflexagon folder called Cherchez la
Femme, the puzzle being to find the picture of the young
lady. Magic and novelty stores also seli an ancient children's
trick usually called the "magic billfold." Its tri-tetraflexagon
ribbon-hinges permit some simple disappearing stunts with
a dollar bill and other flat objects.