Menahot 76: Refining the Flour - Again and Again and Again

2 mishnayot: 1 - All of the grain-offerings require 500 "rubbings" (between hands) and 300 "poundings" (in kneading, for example). With clear heritage of the knowledge, though it has essentially been lost now. 2- The measure of barley of the omer: one-tenth of a se'ah of barley - and the amounts of flour required for not only the omer, but also other grain-offerings. Including sifting the flour for each of them. Which leads into multiple rounds of sifting that is to be used in these holiday offerings.