Close your left eye, and with your right eye focus on the +.  Keep your eyes about two feet from your computer screen, then slowly bring your face closer to the screen.

When you get a certain distance away, the 0 should disappear.  This is your blind spot.
Now, try it with your right eye closed, and focus your left eye on the 0.

Not everyone's blind spot is in the exact same place.  In fact, for most people, the blind spot varies between the left and right eye.