If you're just a bit more cautious on a Friday the 13th, wouldn't fly on Sept. 11 or could never live in a house numbered 666, you are not alone.

With 06/06/06 looming (June 6, 2006), authorities in some cities are worrying prophecy theorists or hate groups might read something ominous into the date and use it as an excuse to stir tension.

Some expectant mothers are making birthing appointments to ensure they avoid the date, according to the Sunday Times in London.

For others, it is a marketing opportunity. Twentieth Century Fox's remake of "The Omen" and Ann Coulter's book, "Godless: The Church of Liberalism," will both come out June 6.

The Beast

The number 666 is used to refer to the Beast — the Antichrist — in the Bible's Book of Revelations:

"He also forced everyone, small and great, rich and poor, free and slave, to receive a mark on his right hand or on his forehead, so that no one could buy or sell unless he had the mark, which is the name of the beast or the number of his name. This calls for wisdom. If anyone has insight, let him calculate the number of the beast, for it is man's number. His number is 666."

Among many coincidences that occur with numbers, life itself is based partly on these three: Carbon atoms, key to life as we know it, have six protons, six neutrons and six electrons in their most common form.

That there is concern over the date at all is a reflection of how popular it's become to search for the hidden meanings in numbers, experts say.

"People have a tendency to latch onto things, like numbers, that help them make sense of the world," said Mario Livio, an astrophysicist and author of 2005's "The Equation That Couldn't Be Solved."

Troubled times

The perceived importance of numbers becomes especially true during troubled times, when finding wisdom in numbers can be a comfort, says professional numerologist Sonia Ducie.

"Humanity and individuals are attracted to numbers during times of great transformation," Ducie said.

The Sept. 11, 2001 terrorist attacks are an overwhelming example. Conspiracy theorists in the years since the tragedy have tried hard to thread together "eerie" numerological coincidences, especially those tied to the number eleven.

A few of the best known:

— 9 + 1 + 1 = 11

— The first plane to hit the World Trade Center was American Airlines Flight 11; AA can also be "translated" as the alphabet's version of 11.

— The State of New York was the eleventh state added to the union.

— The names "George W. Bush," "New York City," "Air Force One," "Afghanistan" and "The Pentagon" all contain eleven letters.

Despite its modern manifestations, searching for deeper meanings in numbers is a practice that goes back to ancient times, Livio said.

"Numerology has a long history," he told LiveScience. "You can trace it all the way from the followers of Pythagoras, whose maxim to describe the universe was 'all is number.'"

Thinkers who studied under the famous Greek mathematician combined numbers in different ways to explain everything around them, Livio said.

Para-science

Modern numerology has since morphed into a kind of para-science in the same vein as astrology, according to skeptics. Still, many numerologists claim to rely on Pythagoras' ancient system to divine the hidden connections between numbers — often a birth date — and an individual's life.

Our attraction to certain numbers has to do with the cycles of birth and death those numbers have seen through many millions of years in existence, said Ducie, who trained at the Connaissance School of Numerology in Royston, Hertfordshire, England.

"People are subconsciously drawn towards specific numbers because they know that they need the experiences, attributes or lessons associated with them, that are contained within their potential," she said. "Numerology can 'make sense' of an individual's life (health, career, relationships, situations and issues) by recognizing which number cycle they are in, and by giving them clarity."

Mathematicians are quick to dismiss numerology as having no scientific merit, however.

"I don't endorse this at all," said Livio, when asked to comment on the popularity of commercial numerology today.

Seemingly coincidental connections between numbers will always appear if you look hard enough, he said.

Lucky numbers

When it comes to lucky numbers, at least, Ducie agreed.

"People can also 'make' numbers lucky simply by believing they will be lucky when they have those numbers around them; these preconditioned thoughts strongly contribute towards their manifestation of luck," she said.

The obsession with particular numbers also tends to wax and wane according to the trends of popular culture, Livio noted.

Dan Brown's mammoth bestseller "The Da Vinci Code" has played a part with its showcase of the golden ratio, or divine proportion, which Livio explores in his book "The Golden Ratio" (Broadway, 2003).

The irrational number — one plus the square root of five, divided by two, or approximately 1.61804 — is said to exist mysteriously in various places in nature and be extremely attractive to the human eye.

Spin-offs in the worlds of architecture, art and even diet books are a result of the "Code" phenomenon.

Ronald Reagan's 666

The supposed number of the devil falls in and out of favor with the public, too. It is unclear just how influential the number was in the centuries after the Bible became widespread as literature, but it was certainly ingrained in popular culture after the 1976 release of the movie "The Omen", in which the neck of a demon-child is stamped with the digits 666.

When former President Ronald Reagan and his wife Nancy retired to their last home in the Bel Air district of Los Angeles in 1989, they forced officials to change their address from 666 to 668 St. Cloud Road, Livio said.

No word on whether the former president, whose full name was Ronald Wilson Reagan, was bothered by the number of letters in each of his first, middle and last names.

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