"The screen size is important, but not the diagonal size.
Theoretically, an 8.9″ screen could range from practically
zero square inches to over 35 square inches. Luckily, it is
possible to use the given information to get a rough (but decent)
estimate of the number of pixels per square inch. Check out the
comparison below: (Pixel densities are in thousands of pixels per
square inch, i.e. TPPSI.)"