Default [Q] how to find out if digitizer works properly in broken nexus 7 (2012)

Hi, a few days ago i broke my nexus 7 screen . There is a huge crack on the screen and the touch works only in a small portion of the screen. The display is coming right though. Also, the broken screen seems to be touching the touch somewhere as the device sometimes responds without even touching the screen. How can i check whether i need to replace LCD glass only or i have to replace the glass along with the digitizer?