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### 5 (five)

The number 5 has some interesting details.

##### Prime number

Five is the only prime number that ends on a 5. From the number 5 on all prime numbers have the form 6*n* ± 1. This is how twin primes develop.

##### Pentagon

A pentagon is a regular polygon.

##### Dodecahedron

A dodecahedron is a platonic body and is the only one made up of regular pentagons.

##### Pentagram

A five-pointed star is called a pentagram.

##### Human body

At each hand you have 5 fingers and at each foot 5 toes. That's why we work with decimal numbers.

##### Office chair

An office chair has at least 5 wheels. This prevents it from tipping over to quickly.