The current world Sudoku champion, obviously at the top of the game, put the numbers together again today. Thomas Snyder, a post-graduate from Stanford, Calif., won the Philadelphia Inquirer Sudoku National Championship at the Convention Center.

The tension was palpable in cavernous Hall A as about 1,000 onlookers -- contestants in the day's earlier rounds and spectators who'd played along with them -- followed the moves of Snyder and his two opponents, Tammy McLeod of Los Angeles and Sarah Ratcliffe of Glenside.

Each stood in front of a large board, each with the same puzzle -- "the most difficult puzzle of the day," announced Will Shortz, the New York Times puzzle editor and host of the event.

Snyder, who finished the puzzle in seven minutes and seven seconds, takes $10,000 in prize money back to Palo Alto, Calif., as well as the promise of a trip to India in March, to defend the title he won earlier this year at the world championship in Prague.

Although Sudoku, the wildly popular number-logic puzzle that has become a daily part of millions of Americans' lives in only three years, has a world championship, today's event marks the first national competition.

Snyder's win, in the advanced division, was the most lucrative, followed by a $5,000 prize for Ron Osher of Stamford, Ct., also a player in other puzzle competitions, who competed in the intermediate-level rounds, and a beginner-level prize of $3,000 to Lori DesRuisseaux, of Elverson in Chester County. "I just came down to have some fun," she said, somewhat startled at her own performance, moments after she won. "I never thought I'd make it to the finals."

A dozen others won $100 each in a bonus round, in which they played against rivals in their age categories. Later, when Ralph Archbold - the city's pre-eminent Benjamin Franklin portrayer - showed up in full costume. He spoke in character to some audience members before taking the stage. "I want to know why there's no over-300 year-old category!" he said. "I would've swept it away!"

The phenomenally popular numbers puzzle - sixty seven million Americans work on at least one Sudoku every day, according to an Inquirer study - has become a national favorite in only three years, since newspapers beginning running it in their features section. Saturday's competition drew people of all ages-the youngest, six, and the oldest, 87-across demographic lines.

"This is the largest Sudoku competition ever held," Brian Tierney, the chief executive officer of Philadelphia Media Holdings, owners of The Inquirer, Daily News and Philly.com, told the applauding contestants.

"And Will Shortz tells me we can now say it's the largest live puzzle tournament ever held in the United States."

Shortz, puzzle editor of the New York Times and the nation's leading puzzle editor, hosted the tournament.

The largest number of players, 442, registered themselves to compete at an intermediate level, followed by 265 beginners and 150 advanced players. At least four of the advanced players have participated in international puzzle competitions. Although most of the competitors were from the greater Philadelphia area, some came from as far away as British Columbia, California, Georgia, Florida and Texas.

"It seemed like something fun and it seemed like something I had a good chance of winning," said Gerhard Paseman, of Oakland, Calif., who arrived at Philadelphia International Airport at 5 p.m. Friday and had to be on a plane back at 6:30 tonight.

The object of the game - which employs logic but requires no skill in mathematics - is to fill in each of 81 squares in a grid with nine rows across and down, and nine 3-by-3 boxes that also cover the grid.

Each row, column and box must contain every digit from one to nine. Between 17 and 33 squares are already filled with a number in each puzzle, and players finish the game by filling in the blank spaces.

A magazine named Pencil Puzzles & Word Games printed the first Sudoku puzzle in 1979, Shortz said,, but it was called Number Place, created by a retired architect from Indiana named Howard Garns.

Five years later, a puzzle editor in Japan printed the numbers game and gave it its current name -- a Japanese acronym for words that mean only single digits allowed, said Shortz, who has researched the history of the puzzle.

Eventually, a retired New Zealand judge named Wayne Gould put together a computer program that could create the game and rate each new version for difficulty levels. The standard current version of the game rates each puzzle between one star, the easiest, and five stars.

It wasn't until 2004 -- two decades later and 15 years after Garns died -- that Gould convinced editors at the Times of London to begin publishing Sudoku puzzles. They became a huge hit with readers and, in only three years, Sudoku has become a standard daily pastime for millions in North America as well. A version of Sudoku now runs in virtually every daily newspaper in the United States.