And note that the difference between 4.5V and 4.545V is 1%, which is almost always less than the uncertainty with which we know any of the quantities we are working with. Thus, for all practical purposes, the two results are equivalent.The calculated 4.5V is actually 4.545V. One writer assumed Vbe=0.6V and you assumed 0.7V. Not theory, just quick, sloppy calculations.