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One in seven human beings are on Facebook.

There are 7,021,836,029 people in the world, according to a recent estimate from the CIA factbook. And about one-seventh of them are on the social network.

Friday morning, Facebook CEO Mark Zuckerberg announced that the massive website had hit a new milestone, with more than a billion active users.

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“Helping a billion people connect is amazing, humbling and by far the thing I am most proud of in my life,” Zuckerberg wrote, announcing the astounding number. The site crossed the billion mark as of Sept. 14 at 12:45 p.m. PST, Reuters noted.

“I am committed to working every day to make Facebook better for you, and hopefully together one day we will be able to connect the rest of the world too.”

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Facebook had 955 million active monthly users as of June, according to a report on Reuters.

Earlier this week, the social media giant unveiled a new feature that lets users pay to promote their posts to friends, just as advertisers do. Facebook has been testing the service in New Zealand, where it tries out a lot of new features, and has gradually introduced it in more than 20 other countries.

Facebook said Wednesday that promoting a post -- such as announcing a garage sale, charity drive or big news like an engagement -- will bump it higher in your friends' news feeds.

"Every day, news feed delivers your posts to your friends. Sometimes a particular friend might not notice your post, especially if a lot of their friends have been posting recently and your story isn't near the top of their feed," wrote Abhishek Doshi, a software engineer at Facebook, on Facebook's news site.

Facebook didn't say how much it will cost to promote the posts, only that it's considering a range of prices as part of the test. On Wednesday, though, some users could see $7 as a cost per each update that they want to promote.

How much will it cost to have a billion people see your news?

The Associated Press contributed to this report.