How do I know the memory that is free on my iPad? It's. 64gb but whenever i'm running any app it's asking to restart as memory is low.... I hardly have any application running..how to know the memory details of iPad?

You are mistaking storage capacity for memory.you can't (without jail breaking) see how much memory you are using on an iPad. Storage you can see under the settings icon, then click on "about". Someone else want to interject?

Have a look for a free app called aMonitor which gives you several pages of information regarding , storage, memory, battery life, MAC address etc., for your particular machine.

Their are several apps in the Apple store that allow you to see memory usage and free up memory. "Free Memory for iPhone and iPod Touch" workd well.

Nice recommendations on apps to show your current memory usage and all, however, I'm wondering why your iPad is asking you to restart, when you hardly have anything running? It sounds like you might be having a h\w issue. I'm still very new to the iPad, but that doesn't sound right to me.