Instagram for Android hit one million downloads in less than one day, and it seems the pace has barely slowed since then — according to Google Play, Instagram has been downloaded more than five million times in about six days. And what a six days it has been, with Mark Zuckerburg opening up Facebook's wallet to snap the photo-sharing service up for a cool $1 billion. That said, there's been a slight amount of backlash to Facebook snapping up Instagram — time will tell if that backlash affects the app's popularity. While we don't expect it'll continue to pull in nearly one million new users a day for much longer, there are still plenty of Android users out who will likely join the Instagram ranks over the coming months.