Mark Zuckerberg may have become the youngest-ever self-made billionaire at the age of 23, but a new regime of underage app developers aren't far behind the Facebook CEO -- in some cases, they're making hundreds of thousands in profits during their after-school hours.

Last week, Apple's prestigious Worldwide Developer Conference (WWDC) opened its doors for the first time to the hundreds of underage technological wunderkinds that it had previously barred from entrance. With legions of teens creating wildly successful apps and launching their own start-up companies, it was high time that the company acknowledge the fresh young faces who are creating some of the most popular apps the company has seen.

For instance, tech ingenue Thomas Suarez, who developed his first app at 12 years old, has already been honored with prestigious awards and given a TED talk about his work (among other apps, Suarez created Bustin Jieber, a whack-a-mole style game that allows users to bonk Bieber's head with a mallett). And 18-year-old blogger Mark Gurman astounded the tech industry when he correctly predicted seven of Apple's super-secret upcoming developments and products.

Check out the slideshow below for a breakdown of the amazing young app developers by the numbers, from ages to profits to number of downloads -- and prepare to be amazed.

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  • 12

    The age of <a href="" target="_hplink">Thomas Suarez</a>, the youngest app developer, who has already created several apps -- such as "Bustin Jieber" and Earth Fortune -- and was honored with a Tribeca Disruptive Innovation Award.

  • 1,599

    The <a href="" target="_hplink">entrance fee </a>to Apple's 2012 Worldwide Developer Conference, which opened its doors to underage app-creators this year. The company gave away scholarships to help cover the fee.

  • 150

    The number of <a href="" target="_hplink">under-18 developers</a> at WWDC 2012.

  • 30,000

    The <a href="" target="_hplink">number of downloads</a> of the app Summly, created by 16-year-old Nick D'Aloisio from Australia. Summly uses complex algorithms to create bullet-point summaries of Web content, such as search results.

  • 250,000

    The amount, in U.S. dollars, that D'Aloisio has made off of <a href="" target="_hplink">Summly</a>.

  • 7.5 Million

    The combined total number of free and full versions of Wooden Labyrinth 3D downloaded. The app -- created by 14-year-old <a href="" target="_hplink">Stephen Huber</a> -- has made it to the number-one spot in the Free Games category in the App Store.

  • 7

    The number of Apple's super-secret new products and upgrades that 18-year-old blogger/tech wunderkind <a href="" target="_hplink">Mark Gurman</a> has successfully predicted. His eighth and final prediction is still yet to be proven.

  • 14

    The age of <a href="" target="_hplink">Aaron Bond</a>, a UK app developer who was expelled from King Edward VI College for hacking into the school's system. Bond has already released six apps and runs his own web design company.