How we could both suffer from the same delusions about the level of incompetence of each other is even beyond me. Ten plus ten is twenty. Ten minus ten is zero. Twenty times zero is zero. I will ask you this, out of all numbers on the real number line, which ones can you factor out a zero? Would one of those numbers be 10? Is zero times something 10? Would that number only be zero? If zero times something cannot be 10, then you cannot factor out a zero from 10. You would have to have 0 x NUMBER = 10, in order for zero to be a factor. Maybe we should go over the factors of 10? 1 x 10 = 10 2 x 5 = 10 I think that is all. Nowhere of these two factors of 10 is there a zero! So why on Earth would you insist that zero is a factor of 10???????????????