What distance extension factor should one follow when tracing an imaginary line from the Big Dipper's 'Pointers' to find Polaris?

Follow that line roughly five times the distance between the two pointer stars

The practical method for locating Polaris using the Big Dipper involves using the two outer bowl stars, Merak and Dubhe, as directional markers. After identifying these two stars—the Pointers—and drawing an imaginary line connecting them, the observer must extend this line outward, away from the bowl of the dipper. The guiding rule specifies extending this line a distance equivalent to approximately five times the original measured gap between Merak and Dubhe. The first relatively bright star encountered along this extended trajectory confirms the location of Polaris, which anchors the end of the handle of the Little Dipper.