For example, we can talk about a mole of atoms which is 6.22 times ten to 23 atoms. But we can't really or it doesn't make sense to talk about a mole of books or a mole of x because I don't think we have this many eggs in the world. Maybe we do, but it's just a very large number. Now, moles and a bogondo's number can be used to answer the following questions. For example how many molecules of water are in 20 grams of water? Now, to answer this question we have to first figure out how many moles are in 20 grams of water.