Adrian Cercenia is a good boyfriend to Cheryl Salacup. But never mind flowers and chocolates; what brightens her mood is math.

In fact, both of them enjoy logic and number mind-teasers, so it's no surprise that Cercenia and Salacup are also Sudoku enthusiasts. Cercenia stoked the romantic fire, so to speak, by giving his girlfriend Sudoku books and the like.

But when Salacup discovered Sudoku's variant, the KenKen puzzles published daily in the Star-Bulletin, she brought it to her boyfriend's attention, and voila! — math love blossomed again. It quickly outgrew the printed puzzles, though, and the couple tried searching online, only to discover that the newly popular math puzzle had little Internet presence.

So Cercenia took his expression of l'amour further and “;gave”; Salacup a Web site — http://www.webkendoku.com, since renamed mathdoku.com to avoid any possible legal complications involving the trademark owner for a similar puzzle, Kendoku.

That love has expanded exponentially. The site attracts an average of 15,000 or so puzzle fans daily from around the world.

The interactive, online version of KenKen was launched on Dec. 10 and now offers close to 1,500 puzzles. The site times players as they work the puzzles, checks their answers and offers a “;gimme a hint”; button for those who find themselves flummoxed.

KenKen, Kendoku and similar puzzles such as CalcuDoku require the player to fill in squares with appropriate numbers, using math operations (addition, subtraction, multiplication, division) as clues.

The easiest puzzles are in 4-by-4 blocks and use only the numerals 1 to 4. The Star-Bulletin offers two KenKen puzzles daily — one easy and one that uses the numerals 1 to 6 in a 6-by-6 block.

The mathdoku.com site ups the difficulty a bit, offering 8-by-8 puzzles along with easier versions.

Both Cercenia, 30, and Salacup, 24, are college students and have regular jobs — he's in the Air Force, and she works the front desk at the Waikiki Beach Marriott Resort & Spa. So their time involved with the Web site is “;all for fun and for the enjoyment of the game,”; Cercenia said.

“;Instead of offering just one new puzzle a day online,”; he said, “;we offer up a randomly generated puzzle out of the many we have on our site. Plus we have a harder 8-by-8 version called 'no-op,' or no operations, which hides the math.”;

“;He's the brains behind this,”; said Salacup, “;and it can be time-consuming to manually process.”;

But it's all done in the name of romance. In fact, Cercenia acknowledges Salacup's “;loving support”; in the site's “;About Us”; section.

So their relationship seems to have a secure future. As for the future of their Web site, Cercenia said, “;I think Sudoku has already hit the peak of its popularity, while Kendoku looks to be still growing. In fact, our site got a significant spike of around 28,000 views when The New York Times added (KenKen) to its puzzle page.”;