The new BlackBerry 10 OS will launch with about 70,000 apps - or 100,000, if you believe what BlackBerry CMO Frank Boulben said in a Q&A at the BlackBerry 10 launch. How does a new OS get to such heights?

Well, about 40 percent of those are Android apps, BlackBerry vice president Martyn Mallick said at another Q&A at the BlackBerry 10 launch. While he didn't do the following math himself, 40 percent of 70,000 is about 28,000 Android apps running on BlackBerry 10 right now.

BlackBerry UX designer Don Lindsay explained how Android apps get onto BlackBerry 10, with its different, gesture-based interface. First of all, you can't just load an Android APK into a BlackBerry phone. Application developers must use the BlackBerry 10 SDK to "wrap" their Android code up in a BlackBerry-friendly form. The SDK translates Android idioms into BlackBerry world: for instance, it maps the Android "menu" button to an up-swipe gesture, and the android "back" button to a back-swipe gesture.

Just wrapping up Android apps is an easy way to fill up a store, but it isn't RIM's goal, Mallick said. That's good, as when you find Android apps on BlackBerry 10, they look odd, with dialog boxes and other UI elements that don't look quite right on the BlackBerry Z10. (See the slideshow for details.) They run smoothly, but they look a little awkward. So Android compatibility needs to be a crutch here, not a mainstay.

BlackBerry agrees. Only truly native apps are eligible for RIM's $10,000 bounty program, and top developers are strongly encouraged to create native apps. That's resulted in 90 percent of the apps from "top app partners" being native, Mallick said.

"From the beginning, our focus has been to get native applications built for BlackBerry 10," Mallick said.

How BlackBerry Picks Its Apps

BlackBerry has an uphill climb ahead of it. Apple's iOS has more than 800,000 apps and Android has 700,000. Even Windows Phone passed the 100,000 mark long ago.

To try to even the score, RIM is targeting the top 100-200 apps in terms of usage in each of the countries it serves, Mallick said. BlackBerry has teams in each country identifying apps and knocking on doors to try to get popular apps' developers to write for the platform, he said.

"There are three components to it. One is the statistical analysis - month by month, who are the top downloads on competing platforms," he said. "The second one is looking at ComScore data to say, what are the brands and services that are getting attention? The third is what I call gut feel: they live in these markets, and can say hey, we know what we see."

RIM's launch event spotlighted well-known games like Asphalt 7: Heat, Jetpack Joyride, and Angry Birds; news apps including The Economist and The New York Times; business apps like SAP, communication apps like Skype and WhatsApp, and many more.

That said, there are a slew of super-popular apps I can name off of the top of my head that weren't in the BlackBerry 10 preview. Streaming video apps are extremely weak - no Netflix, no HBO. Amazon showed but not Barnes & Noble. Instagram is AWOL.

It's difficult to assess how successful BlackBerry's efforts to nurture developers are, because the phones aren't going on sale here in the U.S. for another two months. Mallick promised that many more apps will appear in BlackBerry World by then.

"A lot of partners were able to hit a date of January 30th, but frankly, some other partners have other schedules … what you see in the store today doesn't reflect what's going to be there at availability of the devices," Mallick said.

For more, check out PCMag's hands on with the Q10. Also see BlackBerry Z10 vs. Apple iPhone 5: Spec Showdown and Unboxing the BlackBerry Z10.

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