Mayor Bloomberg, flanked by Chancellor Walcott and new school leaders, discusses the city's school creation efforts.

When Mayor Bloomberg entered office in 2002, there were about fewer than 1,200 schools in the city. By the time he leaves, there will be about 1,800.

That number — representing a more than 50 percent increase — had Bloomberg and Chancellor Dennis Walcott in a good mood during a press conference today to tout this year’s crop of new schools. Thirty Department of Education-run schools will open in September, as will 24 privately managed charter schools.

“We have created so many new schools. It is truly amazing,” said Walcott, who stood with Bloomberg and dozens of freshly minted principals at Manhattan’s Washington Irving High School, which will house two of the new schools. The pair touted a recent study by the research firm MDRC that concluded that the city’s new small high schools have continued to post higher graduation rates than other schools that remained open.

The addition of 54 schools created through the department’s new schools creation process will bring the total number of city schools to 1,750 this fall, 589 of them opened under Bloomberg’s watch. Bloomberg has promised to create at least 50 new schools next year — evenly split between charter and district-run — and he reiterated that vow again today.

Another 26 new schools would open under the city’s “turnaround” proposals but were not included in the small schools total touted today. Those proposals, which are likely to be approved next week, would close and immediately reopen 26 schools with new names and many new teachers in an attempt to win federal funding for the schools.

The sunny event came on the same day as two reports took aim at Bloomberg’s school policies, saying that his administration had fostered inequities and closed schools without first trying to improve them. The city decided this year to close Washington Irving, where teachers have said students had grown increasingly needy in recent years. The teachers also said that the school’s landmarked library, where the mayor’s event took place, had been closed to students since Washington Irving cut loose its librarian last summer.

If the criticism bothered Bloomberg and Walcott, they didn’t show it during their presentation. Instead, the pair engaged in friendly stage banter about the new schools.

Walcott noted that city elementary and middle school students had started state reading tests today. Then he offered a quiz question to Bloomberg, asking the mayor to guess the number of students who attend schools created on his watch.

Bloomberg furrowed his brow and did some quick mental math. “350,000?” he suggested.

The number was way too high. Actually, about 190,000 students — or just over half of Bloomberg’s estimate, which he explained was based on an assumption that a third of the city’s schools would enroll a third of its 1.1 million students  — will be enrolled at the schools in September.

“You’re watching the mayor and chancellor show,” Walcott joked from behind the podium. Then he told Bloomberg that the schools would in fact enroll 384,000 students when they are at full capacity; many are so new that they are still adding a grade each year.

“You’re always right,” Walcott told the mayor, adding, “I don’t want to be an ex-chancellor.”

Cleanup took place in Washington Irving's library after Bloomberg's press conference there today.

Bloomberg and Walcott were less sanguine when discussing the number of schools that would close to make way for additional new schools. The Bloomberg administration has so far closed or begun closing 140 schools, and most of the 589 small schools have opened in space vacated by schools deemed so low-performing that they should not continue to operate.

Bloomberg dismissed a rumor, repeated by mayoral candidate Bill Thompson at an event earlier in the day, that the department would try to close 75 schools in his last year in office.

”We can’t possibly know what we’re going to do next year,” he said, adding that the department would withdraw schools that are improving from closure consideration, as it did two weeks ago when it pulled seven schools from the turnaround roster.

About next year’s closure toll, Bloomberg said, ”Pick a number. It’s less than the total number of schools that are in this city and greater than zero.”