How to Crack a “Master Lock” Combination Lock
Wikihow has an article describing a method for reducing the total number of combinations for a Master Lock® combination lock from 64,000 to 80.
“…there are 64,000 possible combinations on a standard 40 digit Master Lock. With this method, however, you can quickly narrow that down to 80 combinations, a workable number to try if you’ve got the time and the inclination to give it a shot…”
Designer Mark Campos has turned the instructions into an easier-to-follow visual guide.