Glycolysis results in a net gain of how many ATP molecules?

The reaction of glycolysis is the splitting of a glucose molecule into 2 pyruvic acid molecules. The reaction requires the contribution of 2 ATP molecules to start, but in the process liberates 2 molecules of ATP from each resulting pyruvate. Because the process results in 2 molecules of pyruvate, a total of 4 ATP molecules are freed, but because the reaction required 2 ATP molecules to start, the net gain in ATP is 2.