However, the empirical formula for this molecule is C one, H two. In other words, for every two H molecules, there is one C molecule. And if we divide 16 by eight, we also get two the same way we divide two by one. So the way you basically go from a molecular to an empirical formula is you find a common number and you divide it by that common number, making sure that we get whole numbers. So in this case, eight goes into 16 twice and eight goes into eight once. Now, why is an empirical formula useful?