Interestingly, whereas the Bible Code book is all about encoded information in the Bible predicting events, this prophecy for the date of rapture holds no clues from the Bible except the (supposed) date of Christ’s death, and Harold Camping’s personal interpretation of certain words. Here is how he solved the puzzle:

By Camping’s understanding, the Bible was dictated by God and every word and number carries a spiritual significance. He noticed that particular numbers appeared in the Bible at the same time particular themes are discussed.

The number 5, Camping concluded, equals “atonement.” Ten is “completeness.” Seventeen means “heaven.” Camping patiently explained how he reached his conclusion for May 21, 2011.

“Christ hung on the cross April 1, 33 A.D.,” he began. “Now go to April 1 of 2011 A.D., and that’s 1,978 years.”

Camping then multiplied 1,978 by 365.2422 days – the number of days in each solar year, not to be confused with a calendar year.

Next, Camping noted that April 1 to May 21 encompasses 51 days. Add 51 to the sum of previous multiplication total, and it equals 722,500.

Camping realized that (5 x 10 x 17) x (5 x 10 x 17) = 722,500.

Or put into words: (Atonement x Completeness x Heaven), squared.

“Five times 10 times 17 is telling you a story,” Camping said. “It’s the story from the time Christ made payment for your sins until you’re completely saved.
More at SFGate

Convoluted, but I can see why it would be compelling to some Christians. Like many modern-day prophets, this isn’t his first prediction. His previous prediction for Christ’s return (Sept. 6, 1994) was wrong because he made some mathematical errors…