So, with one yellow proficiency die, your chances of rolling a Triumph are 1 in 12. What are the odds of getting at least one Triumph if you're rolling two yellows? And is there a set probability increase with each additional yellow die you roll? (I'm not talking about success vs. failure here; just the raw probability that one of those yellows will come up a Triumph.)
Bonus points if you can show me the mathematical formula for determining the added chances of getting a Triumph with each additional yellow die. I know this is something I learned once upon a time...