The phrase "acknowledged a number" is correct and usable in written English.
It can be used when referring to recognizing or admitting the existence of a certain quantity or amount of something.
Example: "The committee acknowledged a number of concerns raised by the community during the meeting."
Alternatives: "recognized several" or "admitted a variety of".
China has acknowledged a number of the problems.
He spoke excitedly of the area's retail revitalization, but acknowledged, "A number of residents have been priced out".
Dees acknowledged a number of previously unreported instances — separate from those involving Costello — in which his conduct with employees had been called into question.
After weeks of insisting that its review had not turned up any serious errors, Bank of America acknowledged a number of paperwork errors, including incorrect data and misspelled names.
While the company has acknowledged a number of mistakes relating to its losses in C.I.O., an independent review committee of the board determined that those mistakes were not attributable to the risk committee".
Lawmakers and transportation officials throughout the Northeast have acknowledged a number of hurdles, including problems with sorting out right-of-way issues and impacts on freight routes and existing Amtrak service.
Dutch law acknowledges a number of specific contexts in which people have more leeway to express opinions, even a prima facie defamatory opinions.
Also, and while I acknowledge a number of people may be reaching for tiny violins at this point, there are the journalists and broadcasters to think about too.
Members of the international team, while acknowledging a number of very expensive mistakes, argue that most of the financial drag on the company from projects like the $3 billion Dabhol power plant in India could be corrected with further investment.
