During its first quarterly earnings report as a public company last week, Facebook (FB) revealed that it had 955 million monthly active users and 543 million monthly active mobile users. The social networking giant estimates that 8.7%, or 83.09 million, accounts are fake, however, an increase from 50 million accounts in March. Facebook revealed that duplicate accounts amounted for another 4.8%, user-misclassified accounts represented 2.4%, and 1.5% were undesirable accounts, CNET reported. More concerning still, the company revealed in its 10-Q filing that nearly 20%, or 102 million users, accessed the social network solely from their mobile devices during the month of June. Facebook has not yet found a way to monetize mobile usage, and the company’s stock has declined sharply as a result.