For O(n) find something to bound i.e for sum sqrt(n) for 1 thru n, bound by n*sqrt(n). For omega(n) look at back half of sum i.e for sum sqrt(n), back half is sqrt(n/2) thru sqrt(n) bigger than n/2*sqrt(n/2). D&C - look at individual case, then case with 2. Assume about L and R, important part is joining L and R. Greedy - Do best you can with options at hand i.e charging station. E(X+Y) = E(X) + E(Y) E(XY) = E(X) * E(Y) ind