I have forgotten how to figure the weight of an arrow for a particular poundage bow.
Grain per inch X by lenght of arrow + broadhead
Ok that total, is this now divided by the draw weight of the bow?

Plus insert, nock and fletching. No need to divide anything if you just want arrow weight. If you want grains per pound-then divide by weight at your draw.

Most people like to keep the arrow weight in the range of 8 - 10 grains per pound.  Toward the upper end of the scale for hunting, to aid penetration, and toward the bottom end of the scale for target, to flatten the trajectory.  Just weigh the whole arrow when it is ready to shoot, and divide by the actual bow poundage you are drawing.

Not sure that I fully understood your question.

If the answers provided did not specifically answer your question, then please rephrase.