  You should follow the order of operations because you need to get an accurate result. If these rules concerning order of operations would no exist, then each solver will solve an algebraic in a particular way and it is less probable to come to a correct answer.  Considering as an example the following algebraic expression which is solved in two ways: one hand,following the rules and, the other hand, disobeying the rules such that:  `0 + 0*x`  following