Seven is not really a magic number, but does have an uncanny way of appearing in all sorts of odd situations

There are seven different ways of linking four hexagons together.

The Mersenne primes are a special type of prime number. The first five are -

3, 7, 31, 127, 8191

- and they can be expressed as a power of two minus one -

2 - 1 = 3

2 - 1 = 7

2 - 1 = 31

2 - 1 = 127

2 - 1 = 8,191

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For a mathematician, the equivalent of breaking th... [ More ]]]>