For This Cause Celeb, Don't Book the Ritz

* Movie star William Baldwin, who replaced his big brother Alec as president of the liberal-activist Creative Coalition, will be in town next Tuesday to join Housing and Urban Development Secretary Andrew Cuomo in throwing a klieg light on the plight of the homeless.

"Andrew called me and asked me to be involved," the 36-year-old Baldwin told us. They plan to walk and talk among the folks who live on the streets of Washington and spend the night in a shelter, with cameras in tow.

Baldwin, who stars in "The Brotherhood of Murder," a new Oliver Stone film about a hate group, has lived the past two decades in Manhattan. He's upset about his mayor's campaign to clear the streets by arresting homeless people. "What Rudy Giuliani is doing, first of all, is against the law. You can't say that you're breaking the law because you're homeless, and we're going to incarcerate you or put you anywhere we want against your will."

Baldwin said he visits Washington frequently to lobby on First Amendment, arts funding and education issues--a nice upgrade from his college stint fetching coffee and dry cleaning for then-Rep. Tom Downey (D-N.Y.).

THIS JUST IN . . .

* We wished power broker Vernon Jordan Godspeed yesterday as he prepared to leave Akin Gump to start the next millennium in the golden jugular of the Wall Street plutocracy, and we had an interesting chat with him about his rumored $4 million annual salary at Lazard Freres & Co. That would be multiples of his Washington winnings and a soothing balm for a future in which his pal is no longer president. "That number is incorrect," President Clinton's golfing buddy insisted. "It's nobody's business," he added, punctuating his remarks with a few percussive Anglo- Saxonisms. But when we pointed out that our salary estimate comes from an authoritative source, he reverted to "no comment," refusing to say whether it's too high--or too low.

* In less remunerative career news, Washington journalist William Greider--The Post's former assistant managing editor for national news and then for 17 years Rolling Stone's national affairs editor--jumps to The Nation magazine today.

* Breaking with long-established tradition, Hillary Rodham Clinton will miss next Wednesday's ceremony in which her husband, like every president since Calvin Coolidge, will light the National Christmas Tree on the Ellipse. We grew very alarmed when we heard that Mrs. Clinton, who was present at the last six tree-lightings, was dissing this year's rite to attend a dinner for Ira Magaziner. But we were greatly relieved to learn that actually she'll be at a dinner hosted by an Irish magazine. Senate quasi- candidate Clinton will be at New York's Plaza Hotel to give Irish America Magazine's Irish American of the Century Award to Jean Kennedy Smith, who will accept on behalf of her late brother, John F. Kennedy.

She's Got Your Numbers

Danica McKellar is best known as Winnie Cooper, Fred Savage's true love on "The Wonder Years." But she might end up being remembered for her new vocation. "I want to help inspire kids to do math," the 24-year-old actress told us yesterday from Los Angeles, where she has been acting in indie movies and musical theater, including a recent turn as Rizzo in "Grease." "I figure if kids see someone like me doing it--Winnie Cooper was a sweet, wholesome, nice image, not some brainiac--maybe math will be less intimidating for them."

McKellar joins Education Secretary Richard Riley today at the National Press Club to launch "Figure This!," a nationwide campaign to encourage kids and parents to have fun working math problems together and thus improve the abilities of students in the United States, who are lagging behind the math whizzes of other countries. McKellar is a genuine math geek. After her six-season run on the ABC sitcom, which ended in 1993, she graduated summa cum laude from UCLA and last year helped produce an original theorem published in a prestigious physics journal. The paper, titled "Percolation and Gibbs State Multiplicity for Ferromagnetic Ashkin-Teller Models in Two Dimensions," is a "characterization theorem," McKellar told us. Unfortunately, our math-impaired brains recoiled from the rest of her explanation.

"Math is fun, but there are only a handful of people whom I can share it with," she said. "I became so isolated mentally, I became antisocial. I became one of those people who wanders around and bumps into things." Ultimately, she decided to drop her plans to become a math professor, but she's still hooked. "I'll sit down and do it for hours," she said. "There's this one problem that's been going through my head. It's driving me crazy. I'll get it!"