Ten billion is a big number. Google Tuesday celebrated 10 billion downloads from the Android Market, approximately three years after the Market's launch. It took the Android Market 20 months to reach its first billion downloads. Then the pace picked up. It took just five months to reach the second billion; two months to climb from 2 billion to 3 billion; two months more to reach 4.5 billion; and another two months to jump from 4.5 billion to 6 billion. In the last four months the number of downloads jumped from 6 billion to 10 billion.

Now, the Android Market is delivering 1 billion app downloads each and every 30 days.

"None of these apps would have existed if it weren't for the developers who created them," said Google in a blog post. "Every day, these developers continue to push the limits on what's possible and delight us in the process. For that, we thank them."

Google is so happy with the big milestone that it is offering a tempting promotion. It's selling some applications that normally cost between $1 and $10 for a mere 10 cents each. Google will offer a total of 100 applications over the next 10 days--introducing 10 new apps every day--at the near-giveaway price.

[Improvements to Android Market over the last six months might be partially responsible for increased sales. See Android Vs. iOS: Google Revamps Android Market.]

The first batch of 10-cent apps includes: Asphalt 6 HD, Color & Draw for Kids, Endomondo Sports Tracker Pro, Fieldrunners HD, Great Little War Game, Minecraft, Paper Camera, Sketchbook Mobile, Soundhound Infinity, and Swiftkey X. A different set of 10 apps will be available tomorrow.

Currently, the Android Market offers more than 300,000 apps. That includes apps for both Android smartphones and Android tablets. Android users also can install apps from sources other than the Android Market, which means the total number of app downloads to Android devices could be significantly higher.

In comparison, Apple's iPhone App Store launched in July 2008. It took only two and half years--January 2011--for iPhone, iPod Touch, and iPad users to download 10 billion apps for their iOS devices. (The 10 billionth app downloaded was Paper Glider, purchased by Gail Davis of Orpington, Kent, U.K.)

In July, three years after launch, Apple's iPhone App Store reached 15 billion downloads. Again, that includes downloads to the iPhone, iPad, and iPod Touch.

Given Android's stronger sales figures over the last few quarters, the question now is how long will it take Android device users to close the gap with their iOS-using peers? Probably not long at all.

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