I first tried the old trick of holding it up to my ear and listening for the cylinders to click together, but as the internet will confirm, this doesn't work on newer locks. There doesn't seem to be an audible click. The cylinders also seem to have some sort of newer mechanism where you can't feel the cylinders engage except for the second and third ones, so neither of the tricks I used to use when I was a bored child to crack padlocks would work on it. I'm wondering if they've now put some sort of soft covering or something on the cylinders so it's harder to hear/feel the clicks. As usual, once my brain failed me, I turned to the internet.
I found this site, which explains how to find the third digit on Master padlocks by playing around with it and seeing where you can get the dial to stick while turning it and pulling it up on the shackle. It worked the first time I did it, as I got a set of sticky numbers that fits into the pattern described. It took me about a minute to figure out the third digit. The site then explains the possible combinations of digits used by Master, which allows you to narrow down the numbers you have to try to find the first and second digit. A little further googling found this site, which has these numbers all laid out in a table, eliminating even having to do the math.
Probably the dorkiest part of this whole project was realizing that I'd pretty much correctly figured out the math involved when I was in middle school and noticed patterns in the combinations of people's lockers. (My group of friends and I had memorized the combinations to each others' lockers so we could leave each other stuff.) I had noticed that the first and third digit always had the same modulus 4, but then got kind of stuck on the second one having a different one (but always having the same parity as the other two digits). I thought I had missed something, but it turns out that the modulus 4 of the second digit is in fact two off from the first and third. Which makes sense if you think about how the cylinders must look and the angles at which they could be rotated to get different combinations.
After figuring out the third digit and using the table to try combinations of first and second digits, I ended up needing to try about 50 out of the 100 possible combinations, and I got the lock open in about 20 solid minutes (minus a couple snack breaks, beer breaks, etc.) So I guess the labor involved was probably worth more than a new lock, but dammit, it was fun figuring out how it worked, and now I don't have to buy a new lock. Plus now I'm blogging about how much fun I had cracking a lock, which just makes me that much dorkier than you.