We'll get a number below theoretical yield and this number is known as the actual yield of our experiment. Now, to see how far a reaction proceeded, in other words, how close it got to our theoretical yield we simply find actual yield and theoretical yield. We divide two. So actual yield divided by theoretical yield multiplies that by 100 to get our percent because otherwise this guy is a fraction and that will give you percent yield. Now, let's look at the following reaction. So in the following reaction, 1 mol of methane reacts with two moles of oxygen to produce 1 mol of carbon dioxide and two moles of water.