Let's go back to the definition of division: If we have a number o apples a and b persons to share them with, we can say that each person gets a/b apples. Example: 4 apples and 2 persons : 4/2= 2 apples for each person or 4 apples and 1 person : 4/1=4 apples Does it make any sense for these apples to be distributed to 0 persons? No. The main mistake is that people assume 4/0 is 0. In fact, the apples are still there (4/0 equals 0), but there are no persons to share them with. So a/0 is undefined, for any a= real number. Extra eplanation: graph method.