# 12

= 2 × 2 × 3

= 2 × 6

= 3 × 4

= 2 + 4 + 6

= 3 + 4 + 5

A dozen.

There are 12 months in a year.

12 inches in a foot and 12 old pennies in a shilling.

12 o'clock is midday or midnight. There are 12 signs of the Zodiac,

12 apostles and 12 people in a jury.

A dodecahedron has a regular pentagon on each of its 12 faces. It is one of the five Platonic solids. It has 20 vertices (or corners) and 30 edges. If you join together the centres of the faces of a dodecahedron you get an icosahedron.

Both octahedrons and cubes have 12 edges. An icosahedron has 12 vertices or corners.

The wheels of most cars are held on by 16 wheel nuts, with four for each wheel. Two important exceptions to this rule are the Citroën 2CV and the Robin Reliant which each have just 12 wheel nuts. The Citroën 2CV has three wheel nuts on each of its four wheels, while the Robin Reliant has four wheel nuts on each of its three wheels.

*On one hand you
can count off the numbers from 1 to 12 by touching the joints of your
fingers with your thumb. There are many good arguments for counting in
twelves rather than in tens.*

** There are 12 ways of arranging
eight queens on a chessboard so that no queen can capture any other queen
(not counting rotations and reflections as being different). Can you find
one of these chessboard arrangements?**

Under British law, when you reach the age of 12 –

- you can watch a 12 certificate film,
- you can buy a pet,
- you can be trained to participate in dangerous public entertainments subject to the grant of a local authority licence.

*12 parallelograms
fit together to make this pattern. What are the internal angles in the
parallelograms?*

Twelfth Night or the Feast
of Epiphany on January 6 marks the end of the Christmas period. It used
to be a time of great merrymaking. Shakespeare's play *Twelfth Night
*was written to be performed as part of the Twelfth Night celebrations.

*A cartwheel with
12 spokes. What other symmetry patters occur in wheels?*