# Puzzles

## Archive

Show me a random puzzle**Most recent collections**

#### Sunday Afternoon Maths LXVII

Coloured weightsNot Roman numerals

#### Advent calendar 2018

#### Sunday Afternoon Maths LXVI

Cryptic crossnumber #2#### Sunday Afternoon Maths LXV

Cryptic crossnumber #1Breaking Chocolate

Square and cube endings

List of all puzzles

## Tags

colouring coins 2d shapes area square roots mean folding tube maps integration graphs dodecagons arrows grids christmas multiplication cryptic crossnumbers money ave perfect numbers geometry advent remainders crosswords quadratics sport probability unit fractions routes irreducible numbers triangles integers hexagons star numbers balancing doubling clocks triangle numbers rectangles scales fractions bases differentiation surds regular shapes means digits books menace polygons multiples symmetry indices chess chalkdust crossnumber time planes factorials cryptic clues calculus addition circles dice pascal's triangle sums prime numbers spheres crossnumbers odd numbers division algebra square numbers squares cards numbers palindromes cube numbers lines chocolate trigonometry averages sequences sum to infinity functions percentages ellipses probabilty people maths dates 3d shapes proportion complex numbers partitions coordinates logic parabolas angles shape floors perimeter factors rugby speed taxicab geometry shapes number games volume wordplay## 21 December

This year, I posted instructions for making a dodecahedron and a stellated rhombicuboctahedron.

To get today's number, multiply the number of modules needed to make a dodecahedron by half the number of tube maps used to make a stellated rhombicuboctahedron.

## Folding tube maps

Back in 2012, I posted instructions for folding a tetrahedron from tube maps. When tube maps are used, the sides of the tetrahedron are not quite equal. What ratio would the rectangular maps need to be in to give a regular tetrahedron?