We use two ATP, two orthophosphates two H plus ions and that produces two ethanol molecules, two ATP molecules, two H so molecules and two carbon dioxide molecules that came from this process. So we multiply that by two and that's where that actually comes from. And notice the NAD pluses and Nadhs are canceled out because they are regenerated in this step. Now what about lactic acid fermentation? So lactic acid fermentation is used by many prokaryotic cells so bacterial cells that we're going to discuss in just a moment as well as many eukaryotic cells. In fact, the cells of our body also use under some circumstances, lactic acid fermentation.