So we have a result of net two ATP molecules. Remember, glycolysis actually forms four but it uses up two. So we form a net of two ATP molecules. Now, glycolysis also forms our two NADH molecules and each one of these NADH molecules eventually end up in the electron transport chain. And because we have two NADH molecules form in glycolysis, we form two times two. So four ATP molecules, for a total of six ATP molecules form either directly or indirectly by glycolysis.