In the fairytale Sleeping Beauty, the 13th and wicked fairy is denied an invitation to the feast to celebrate the birth of the king and queen's daughter and so she casts an evil spell.

Some people don't leave their home if it's Friday the 13th and hotels rarely have a Room 13 for their guests to sleep in.

A lot of superstition is connected with the number 13. Therefore, the year 2013 is set to be an interesting one for mathematicians, mystics and the superstitious.

"I like to play around with dates and numbers because it's fun," says Heinrich Hemme, a professor of physics at the University of Applied Sciences in Aachen, Germany.

So what does he make of 20 minus 13 equals seven? "In many cultures seven is a lucky number."

And what about 20 plus 13 equals 33? "That's the age that Jesus died."

The author of a recent opinion piece in The Economist noted that 2013 will be the first year since 1987 to have all digits different from one another.

Hemme's enthusiasm for the year 2013 gets going when he points to the sum of all the numbers in the year: six.

"Six is quite special and rare. Six is a perfect number and is equal to the sum of its positive divisors. The next perfect number is 28."

Since the year 1500, the only years to have produced a perfect figure are 1999 and 2004. There are two Fridays in 2013 that will fall on the 13th of a month: in September and December.

According to Hemme, there is no other combination of weekday and date more frequent than the two Friday the thirteenths in 2013.

"But that has nothing to do with superstition. It's pure math."

Does Professor Hemme have any worries at all when he thinks about the new year?

"I'm not the slightest bit concerned," says Hemme, who does not have a favourite number.

But many people are superstitious when it comes to "unlucky" numbers.

"Any type of belief can provide security," says psychologist Peter Gross.

That can express itself in belief in God, fairies or numbers.

That helps create a sense of security.

"It gives a feeling of knowing something that you can protect yourself with," says Gross.

"Susceptibility to superstition is directly correlated to levels of education."

The higher the level of education, the more rational a person will be.

"That's because education systems are constantly demanding rational and logical thought," says the psychologist.

But some forms of superstition develop over a period of time due to selective perception.

"What most people believe, is perceived as being the truth and is rarely questioned."

Friday the 13th is considered an unlucky date across Europe.

Greece is the exception where Tuesday, and not Friday, is thought to be the unlucky day.

The Chinese can be very superstitious when it comes to numbers but neither 2013 nor 13 are considered unlucky. However, it's a different matter when it comes to the role 2013 plays in the spoken word.

The Chinese for 2013 sounds a little like, "I will love you all my life".

A good day to get married in China would be January 13th, 2013 because of the double presence of 13. In Chinese that date sounds a little like, "I will love you all my life and for another lifetime as well".

In France the figure 13 has a number of associations. Some people try to avoid sitting at a dinner table with that number of guests.

But in the Provencal region, 13 desserts are traditionally served at Christmas, including dried fruits and special seasonal cake.

Tarot cards are thought to have their origins in France and the 13th card is represented by death.

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