And when talking about the running time of an algorithm with O-notation, concerns about whether or not an algorithm is faster by a constant factor (for example three times faster, an order of magnitude faster, two orders of magnitude faster) compared to another algorithm is not captured by the O-notation by convention (it is abstracted out, so to speak). If you find out that an algorithm is O(2n), you simplify it to O(n) (the coefficient of n does not matter).