When Anne Gilman showed up for classes yesterday at Alexandria's T.C. Williams High School, she told exactly one person her good news. That was during second period.

But news like that can't be cornered, and by day's end "several hundred people knew" Gilman's secret -- that she had scored a perfect 1,600 on her SAT tests this fall, one of 13 students nationwide to do so.

Gilman, 16, said she expected to receive good scores on the two-part entrance exam, a nervous ritual for college-bound high school seniors, but that even she was surprised when Monday's mail brought her test results.

"I was fairly confident I would do well, but not that well," she said yesterday.

First things first. She called her parents. Her mother, Judy, sent balloons; her father, Alfred, "took us out to dinner," she said.

Getting perfect scores of 800 in both the verbal and the math skills sections of the SAT is "extremely rare," said Janice Gams of the Educational Testing Service, which administers the exams for the College Board, an association of 2,500 colleges and secondary schools. The SAT was administered to 1,810,348 students this fall.

Gams said she could not provide details about the other students who had perfect scores because such information is confidential.

Spokesmen for other Washington area school districts said yesterday that they knew of no perfect scores locally. The Educational Testing Service does not send a list of the scores, so the only way officials would know is by word of mouth.

Last school year there were nine perfect scores, Gam said; the year before there were eight. Virginia students this year had mean scores of 434 in the verbal exam and 473 in the math exam, she said (half the scores fell above those numbers, and half were below).

Gilman, whose older sister, Nancy, is studying mechanical engineering at MIT, said she prepped herself mentally before taking the exam. "I made it a point to calm myself down. I cheered myself . . . . You say {to yourself}, 'It's just a stupid test.' You pretend it's practice."

Gilman, who entered first grade at age 5 because she could already read, said she does not study a lot -- on average "maybe two hours" of homework each night, "and that's a fairly generous" estimate.

When not studying, Gilman likes "to see movies, see my friends, listen to the radio and talk on the telephone. I also like to read non-great literature," she said, especially science fiction. Athletics is "one area in which I show an obvious lack of talent," she said, although she does take an aerobics class.

Gilman acknowledged that students such as herself risk being stereotyped. "People think you're a nerd or mutant or whatever," she said. "But I . . . don't try to fit too hard into the normal status . . . . I certainly don't consider myself more gifted than most of my friends. Maybe I'm talented in certain things like SATs, but there are some things {my friends} do better."

"People tend to overemphasize SATs," Gilman said yesterday. "Not all talents are measured on {them}. I don't understand mechanical engineering. Do you?"

Gilman is applying to seven colleges and hopes to pursue interests in writing, foreign languages and the application of computers to education. She also is interested in politics.

Asked, with an apology for the cliche, what she wants to be when she grows up, Gilman replied: "That's a good question. May I use a cliche to answer?

"I don't know."