Sunday is the big day for saying “I do.”

More than 39,000 couples chose 10/10/10 as their wedding day — a nearly tenfold increase over the number of nuptials on Oct. 11, 2009, the comparable Sunday last year, according to figures gathered by David’s Bridal, the wedding superstore chain.

The reason for the surge is a blend of superstition and symbolism, said Maria McBride, the wedding style director at Brides Magazine. “You cross your fingers and hope it lasts a lifetime,” she said, and so “a perfect 10, times 3” suggests good luck.

Besides, Ms. McBride said, “You’ll never forget your anniversary.”

At the Viva Las Vegas Wedding Chapel, the owner, Ron DeCar, has 150 ceremonies planned in five chapels, beginning at midnight. He has had to hire extra Elvis impersonators, he said, to bring the contingent to six.

There was a similar surge on July 7, 2007, and he is already planning for 11/11/11 and 12/12/12.

For those of a geeky bent, the date has another layer of importance — it is made up entirely of ones and zeros, the binary language of computing. Kevin Cheng and Coley Wopperer of San Francisco have been waiting nearly two years for their wedding date to roll around, having realized over dinner with friends in 2008 that, as one suggested, “you could have a binary-themed wedding!” he recalled.

“Both of our eyes just lit up,” he said.

“We’re very much technology people,” Mr. Cheng explained, as if it were necessary to point this out.

The dinner group quickly calculated the more familiar base-10 value of the binary number 101010, and found that it was 42. “That totally sealed the deal!” he recalled.

Footnote: For fans of Douglas Adams, author of the series of science fiction comedic novels beginning with “The Hitchhikers Guide to the Galaxy,” the number 42 is instantly recognized as the punch line to one of literature’s most revered shaggy dog stories. In it, super-intelligent beings have created the most powerful computer ever to provide the “Answer to the Ultimate Question of Life, The Universe, and Everything.” The computer labors for 7.5 million years. Finally, it answers: “Forty-two.”

Which means, gentle reader, that Kevin Cheng and Coley Wopperer are truly meant for each other.