How to Quit Multiple iPhone Apps Simultaneously in iOS with Multitouch
If you ever need to quit out of more than one app on the iPhone, or quit a bunch of apps quickly in iOS, using a handy multitouch swipe gesture at the iOS multitasking screen is enough to quit apps simultaneously. This works really well to quickly clear out the multitask bar of all running apps if you need to for whatever reason, and you can quit as many apps at a time as that fit on screen (and that you can fit fingers onto), which usually means killing running apps in groups of three.