An entire Bronx charter-school class in the nation’s poorest congressional district not only passed the Algebra I Regents exam — but aced it, officials told The Post.

A total of 53 eighth-graders at Success Academy Bronx 2 in Concourse Village — where 90 percent of students qualify for free lunch — conquered the rigorous test with rankings of 5 out of 5, according to the charter school’s network.

That mark corresponds to a score of 85 or higher on the math test.

School administrators announced the triumph at a graduation celebration last week, sending parents and relatives into a joyous frenzy.

“The collective pride in the whole room was through the roof,” said Principal Todd Gentilcore.

“The parents were cheering, the teachers were cheering, the kids were cheering.”

Taking the test in the eighth grade puts students in a position to tackle advanced math courses like calculus in high school. Passing the exam earns high-school credit and scores are reflected in transcripts.

All 467 Success Academy eighth-grade students across their network took the test this academic year, and 99 percent passed with a minimum rank of 3, or a score of 65.

Of that group, 56 percent scored at the top level of 5.

At traditional public schools, 34 percent of all eighth-graders took the test in 2017-18 and 82 percent passed with a minimum score level of 3, according to the city Department of Education.

The percentage of students who notched a score of 5 was not immediately available, a DOE spokeswoman said.

The teacher who orchestrated the Bronx charter school’s unlikely feat, Karina Mateo, said she conveyed to her students that simply passing the test was not adequate.

“I’m not going to lower the bar,” she said. “My idea is that not only can everyone do math, but that they can excel at math. I told this to parents and they believed me.”

Mateo said she emphasized how critical the subject is to ultimate success and stressed the overall benefits of sustained diligence and focus.

“If you can do that, a lot of doors open,” she said. “If they understand why it’s important, then they’ll buy into what you’re doing.”

While most of the grads will go on to enroll at Success Academy HS of the Liberal Arts, six members of the class will attend specialized high schools next year, the network said.

With its opponents holding sway in Albany, the charter-school sector is facing punishing political headwinds.

Charter opponents accuse the schools of siphoning money from the traditional public system, pruning problematic students and failing to ensure proper transparency.

Success Academy, considered a sector leader, has also come under fire for what some parents and politicians have deemed excessively rigid discipline and suspension policies.

Despite those critiques, demand for charter seats continues to swell — especially in poor minority communities with grim schooling alternatives.

Chronic underperformance continues to plague large swaths of the city, especially at the middle-school level.

The Post reported on Sunday that critics are warning of widespread “grade inflation” in DOE schools — where kids who aren’t passing state English and math proficiency exams are still being graduated from grade to grade.

There were 52,700 students on charter waiting lists this past academic year but lawmakers declined to lift the cap on expansion of the sector.

Roughly 10 percent of all city kids are enrolled in charter schools.

Both Mateo and Gentilcore said they were perplexed by the mounting opposition to standardized testing as a means of academic measurement.

“It’s obviously not the be-all, end-all,” Mateo said. “But we need to know that these kids have mastered some basic concepts and are set up to do well in the future. It’s as simple as that.”

Gentilcore said some formal testing assessment is crucial to ensure accountability for students — and the adults who oversee their education.

“If I don’t have that metric, how do I know how these kids are doing or if they are prepared for the next level?” he asked.

The Bronx school is located in Congressional District 15, which has the lowest median income of all 436 districts nationally, according to census data.

“Most of these kids are first-generation immigrants,” Gentilcore said. “They come from Puerto Rico, the Dominican Republic, West Africa. These are hardworking families, and their kids work hard as well. All they need is a teacher like Karina to help them.”

Gentilcore said many parents have forgotten basic algebra by the time their children tackle the topic in school and are sometimes unable to directly assist them.

“But what they can do is help to establish strong work habits,” he said. “Making sure they are taking the time every night to study. Making sure they do what they have to do free of distraction.”