Apple expected to hit 50 billion app downloads by Wednesday by Philip Elmer-DeWitt @FortuneMagazine May 14, 2013, 11:35 AM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons 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.