then because you always propagate the error according to that what you'll have in each in each layer is basically a vector target so it's no longer just one number but each layer now has a target of vectors and it says okay these are the outputs that would be beneficial please this layer please change your outputs in the direction of negative two negative three plus four so you see this is so the negative two would be this unit the negative three would be this unit and the plus four would be this unit so each unit is instructed