Apple expected to hit 50 billion app downloads by Wednesday

FORTUNE –Apple (AAPL) loves those big numbers with a lot of zeros, and for the past week the company has been promoting — with prizes, cool facts and a countdown odometer — another fast-approaching milestone: The 50 billionth app download.

Hard to believe it’s been only 15 months since the last one.

  • 1 billion: April 2009
  • 10 billion: January 2011
  • 25 billion: February 2012
  • 50 billion: May 2013

As of 1 p.m. EST Tuesday, apps were being downloaded at the rate of 813 per second. At that speed, the App Store would hit 50 billion by 12:39 p.m. Wednesday.

But we expect things to accelerate as the goal approaches.

The customer who downloads the 50 billionth app wins a $10,000 iTunes gift card. See Contest rules.

Subscribe to Well Adjusted, our newsletter full of simple strategies to work smarter and live better, from the Fortune Well team. Sign up today.