His math is right, but more advanced than that of the “typical” test taker.

After an East Setauket teen said he discovered a flaw in a Regents Geometry exam question, the state Education Department acknowledged his finding was correct, but said he used concepts beyond those taught in the course.

Ben Catalfo, 16, an incoming junior at Ward Melville High School, started an online petition Monday to force the department to rescore the test, giving students credit for Question 24 about two mathematically similar triangles.

Catalfo, a math whiz who passed the exam in seventh grade, maintains that none of the four choices is right.

Department officials said Catalfo solved the problem using advanced mathematical concepts and that based on the level of geometry taught in the course, Answer 2 is correct.

“Mr. Catalfo is clearly an exemplary student of math with skills far above most students his age,” said department spokeswoman Emily DeSantis. “He used mathematical concepts that are typically taught in more advanced high school or college courses.”

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The exam questions are written by experienced geometry teachers and field tested with a representative group of geometry students in schools across the state, DeSantis said.

Department officials declined to comment further.

Catalfo’s petition, which had more than 2,200 signatures by Friday morning, follows outcry over the revamped exam, which parents and educators have argued is too difficult and to blame for falling student performance.

The department also acknowledged that two questions out of 36 on the exam administered June 16 had more than one correct answer.

Catalfo discovered the flaw while tutoring other students for the exam. He shared his finding with his father, Anthony Catalfo, a math tutor, and William Bernhard, his former principal at P.J. Gelinas Junior High School, who is also an adjunct math lecturer at Stony Brook University.

They all came to the same conclusion.

Ben Catalfo believes the state’s response is referencing his use of the law of sines, a concept that isn’t taught in the course.

“It’s just one of the many ways of solving the problem,” he said. “Their [the department’s] arbitrary rules about what math students should know and shouldn’t know shouldn’t contradict what is true.”

Anthony Catalfo said he is disappointed by the department’s response to his son.

Benjamin Catalfo, 16, of East Setauket, demonstrates on Tuesday, July 18, 2017, the mathematical proof he used to find whe he considers an error on the Regents Geometry exam. Photo Credit: Newsday / John Paraskevas

“What’s happening here is they’re penalizing you for thinking deeper,” he said. “They should reward that, not penalize it. It doesn’t make sense to me.”