Can the combination of a Master Lock be found though manipulation?
Recently a method of finding the combination of a Master Lock has been presented on alt.locksmithing. It seems there is a formula that relates the numbers in a combination to each other. The first and last digit of any combination will both have the same remainder when divided by 4, and the second digit’s remainder when divided by 4 will be – or + 2 from the first and third’s remainder. For example, if you knew the last digit of the combination was 5, the first digit could be any digit that had a remainder of 1 when divided by 4 and the second number any digit with a remainder of 3 when divided by 4. This means given one number in the combination, there are only ten numbers that can be in each of the other two positions, and thus only 100 possible combinations given one number in the combination. This “modulus 4” constraint does not appear to apply to “current” production locks (1999?-). And it turns out there is an easy way to find the last digit of the combination. On older Master Lo
