Hi reader ,

The parallel axis theorem states that, the moment of inertia of a body about any axis is equal to the moment of inertia about parallel axis through its center of mass plus the product of the mass of the body and the square of the perpendicular distance between the two parallel axes.

If the moment of inertia known for axis through center of gravity of object and want instead of center the moment of inertia at the edge. Can use the parallel axis theorem to find that instead of reworking everything from the new axis.

i hope this helps

thank you