Fairfax County school students are discovering a solution to their math problems: the telephone.

By dialing a number in Northern Virginia (644-0330) on Wednesdays between 7 and 9 p.m., students can have their math homework done for them. Or at least they can get a teacher who will stare at them from a television screen until they swear they understand how to get the answer.

It's all a part of a new cable-TV program in Fairfax County called Dial-A-Teacher, and the prospect of having a teacher in the living room hasn't deterred the hundreds of students who have flooded the show with questions since it began four weeks ago.

"Most of the calls are math questions because, beyond a certain level, the parents can't help anymore," said Leslie Jessell, one of the two teachers who fielded questions Wednesday night.

And math problems, unlike literary ones, can be definitively resolved.

But there are a lot of math questions being asked each night in a school system with 124,000 students. That's one reason math teacher Myrna Walters gives two hours to the program, which is sponsored by the Fairfax Federation of Teachers. Walters compares it to being on a game show without the risk of being caught without the answer when the buzzer sounds.

"I'm plenty prepared for anything a high school kid can throw at me," she said this week. "So if this were 'Jeopardy,' I wouldn't be here. It's because it's limited to math that I'm here."

But that was before Wednesday's question on Russian multiplication.

"I want to know about lattice multiplication," said the young caller. Like other questioners on Dial-A-Teacher, he was not asked to give his name.

"You'll have to explain what lattice multiplication is," Walters said, her show-biz smile looking a bit strained.

"Well, I have it on a worksheet which also has Russian multiplication. It says, 'Correct Russian multiplication by using lattice multiplication.' "

Walters began scribbling the words on the blackboard, but the problem grew more complicated. "What we have to do," said the caller, "is solve Russian multiplication problems by using the Russian peasant method."

The Russian peasant method?

Walters never found out what that was, even after the caller described a diagram in his book.

But, with some clever repartee and some quick geometry, Walters charmed her caller. He signed off, without a solution, but satisfied. (Walters later searched a math book and failed to find an answer, but she did discover a definition for lattice, a partially ordered set of numbers placed around a matrix.)

"In class, not all the students appreciate you," Walters said. "But at Dial-A-Teacher, I find the kids really appreciate me. They need you, so they're very polite."

The calls to Dial-A-Teacher come from students of all kinds -- from fourth graders struggling with fractions and college students laboring on probability theories, to mothers who've gone back to school and don't dare ask their children for help.

The typical caller, according to John Lam, the elementary schoolteacher who conceived of the program, is "the kid who might be shy in class, who's afraid to raise his hand and ask a question."

Or it's the student who thought he understood it all in school, but came home to find "it's just Greek again," said Lam. "What the child might need is just somebody to refresh him."

For the student, the program can mean a good night's sleep. For the teacher, it can mean a satisfying day.

"In a class, you're dealing with 30 kids . . . and there's no way to make sure they're all with you," says Walters, "whereas you get a constant feedback here, there's more give and take . . . and it's always more personal." Even through the camera.