Frank Lu earned a 34 when he took the ACT college entrance exam last year, just a smidgen below a perfect score.

Unwilling to settle for that, the Minnetonka teen took the test again in mid-June, and he got that perfect 36 — as an eighth-grader.

“It is truly remarkable,” said Katie Wacker, the ACT’s spokeswoman.

ACT officials don’t keep formal statistics on perfect scores by grade, but Wacker said she found fewer than 10 eighth-graders with perfect scores over the past five years.

Even among all ACT test takers, all the way up to 12th grade, a perfect score is rare. The high school graduating class of 2014 saw about 0.10 percent out of 1.85 million students earn a 36 when quizzed in English, math, reading and science.

Frank’s father said his son, who is strongest in math, didn’t use a tutor or put in an extraordinary amount of time before the June 13 do-over.

“He borrowed some ACT books from the library and just kind of practiced for two weeks,” said Wentao Lu, a computer scientist for U.S. Bank. “It was quite a surprise to us. We thought maybe a 35 [this time].”

Frank, who is leaving behind Minnetonka East Middle School and looking forward to ninth grade at Minnetonka High School, said he’s signed up to take the ACT at such a young age as he pursues enrolling in the Northwestern University Center for Talent Development, a gifted student program based in Evanston, Ill.

He intends to take the test again as an 11th-grader as he starts to look into his options for college.

In the time since Frank learned of his perfect score, he has kept the news to himself.

“I haven’t told anyone,” he said. “I kind of don’t want to come off as a pretentious brat. It’s not the optimal.”

Away from studies, Frank plays piano and enjoys listening to music. He said he hasn’t given much thought to a career path and intends to stick with his same-age friends and “try not to graduate [high school] early,” he said.

Frank has two siblings, a 3-year-old sister and a brother who just finished sixth grade. Wentao Lu said his younger son tagged along with Frank and also took the ACT in mid-June. Winston got a 27, not perfect but well within the range that most colleges — and parents — find acceptable.