How to scale the mc to the entire page

Hi there, I had done a mc and want this mc to scale until fits the entire screen(center of the screen) after have some motion tweening. So how could I do that ? Notice that my MC location is from everywhere, that means it can come from left, right, bottom left, or bottom right, and I want it to scale until fits the entire screen. I have some script here:

onClipEvent(enterFrame)
{
	if(_root.card._currentframe == 31) //after it had done some motion tweening
	{
		_root.card.stop();
		_root.card._xscale += 70;//start scaling
		_root.card._yscale += 70;//start scaling
	}
}

The code above its just a normal no-ending scaling, so how can I archieve my requirements. Someone please guide me, thanks!