Since 6 / 3 = 2, then, if we were to solve for 6, 2 * 3 = 6. Now, what if we have 6 / 0 = x. By that statement, if we were to solve for 6, 0 * x = 6. That is impossible for anything multiplied by 0 is 0. This is basic algebraic math. Now, whether it is taught in calculus (not in it yet) that you can divide by 0, I don't know. Just enjoy the information.