Hello... I'm trying to figure out how many magnets I need to put on one side of a piece of sheet metal in order to sufficiently magnetize all the surface area of the other side to a specific attractive force to other pieces of steel in contact with the sheet. It has been too long since college. I can't remember how to calculate this. Is it rude to ask here? It's not for commercial use. I want to magnetize a big piece of sheet metal, hang it in my garage, and keep tools on it, wrenches and sockets and such.