like for any algorithm? On wikipedia it lists for multiplication it's O(n^2) but some of them have decimals like O(5/2n^2.2342) or something so how would you determine that? Just use a computer and make a graph of input in bytes vs time in seconds and fit a curve to it? Like I understand for eg the problem of determining if theres exists a subset of integers in another subset of integers such that they add to 0: If the algorithm was to check each subset, if theres n integers then theres 2^n-1 subsets to check, but then youd have to add each one -so that would count as a step? so theres 2^n+n-1 steps for an input of n ..does that mean its on the order of O(2^n) ?