Now that you have the third number cracking the lock is a breeze!  You will now be able to narrow down the combination to one of 100 combinations.  Sound like a lot?  Fine, try all theoretical 12,000 combinations yourself....

Do you know what a modulus operator (represented with a %) is?  No?  Wrong, you do; you just haven't used it since elementary school and you didn't call it modulus back then.  Modulus is the remainder after you divide something.  Example:  21%2=1.  This is because 20 divided by 2 is 10 with a remainder of 1.  23%3=2, because 23 divided by 3 is 7 with a remainder of 2.  A note about modulus: you answer will never be greater than what you 'modulused' by minus 1.  For example, you can't have a remainder of 3 when dividing by 3, because you can do more division.

Solve the third number in the combination modulus 4.  Let's say you found that the third number of the combination is 28.  28%4=0 (28 divided by 4 equals 7, with a remainder of 0).  Let's call that number X; you will now use X to get the first and second numbers of the combination.

Take X and add 4 to it.  Add 4 to the new number.  Add 4 to that number.  Keep doing this until you have a list of ten numbers.  Why ten you ask?  Because contained within this list is the first number of the combination.  Since these are possible first numbers, if they are separated by four notches you can't have more than ten of them on a lock that has 40 notches.  If your first number was 0, then the ten numbers would be 0, 4, 8, 12, 16, 20, 24, 28, 32, and 36.  The starting number for this list will be a 0, 1, 2, or 3 (you can't have a remainder of four or anything higher than that when dividing by four).  As stated above, one of those ten numbers is the first number of the combination!

Now take that original number and add or subtract 2 to it, let's call this new number Y.  If its a 0 or a 1, add 2 to get Y, if its a 2 or a 3 subtract two to get Y.  Why do you add or subtract when you do you ask?  Pretend this new number, Y is something else you got in a 'something%4=Y' equation.  If you think that way, you know Y cannot be a four or greater, and cannot be a negative number, this will tell you when to add or subtract.

Now do the same thing to Y that you did to X to get another ten numbers.  If the first number in the first list of ten was 0, your first number in the second list of ten would be 2.  Thus your second list would be 2, 6, 10, 14, 18, 22, 26, 30, 34, and 38.  One of those numbers is the second number in the combination!

You now have ten possibilities for the first number, ten possibilities for the second number, and one possibility for the third number.  Doing a little math you can see that you now have 10*10*1=100 possibilities to try.

To try all the combination, I like to try the first number in the first list of ten, with all ten number in the second list of ten (one at a time obviously) followed by the last number.  If I don't find the combination I can forget about the first number in the first list and move on to the second.  On average it will take 50 tries to open the lock.  The amount of tries it takes on several locks will follow a bell curve, with the highest point being at 50 tries.

Once you have this method down you can move on to method two for getting the 1st and 2nd numbers.  Do so by clicking the '1st/2nd# Method 2' button to the left.  The second method is very confusing at first, but is a little easier on the fingers (i.e. less movement) and takes the number of tries down to a max of 80.

If after trying all these combinations you still haven't found the correct combination, you may have done something wrong.  Check your work and make sure you found the correct third number.  Maybe you missed one of the combinations when trying to crack the lock.  It's also possible that the lock you are trying to crack is too old or too new to crack.  But remember, just because your cracking a lock that was just bought, it doesn't mean it was new.  A lot of stores sell locks that have been sitting around for a while and are actually old enough to crack.  It's only extremely new locks that this method won't work for.  Also, make sure the lock is actually a Master, as CVS brand, American brand, et cetera won't open using this technique.