Maths does not escape me. I understand what OP is saying and what you are saying. But you do not understand what I am saying. The probability that in any given week that a given piece of armor will drop is 1 in 6. For the same armor to appear 4 times in a row I agree with OPs comment that it is 0.07703% No, the chances of rolling a six on a regular die 20K times in a row are (1/6)^20K i.e. highly unlikely and pretty close to impossible, but the chances of a six rolling on the 20,000th time is 1 in 6 and every other time. A question, what is the chance of Voidfang appearing next week? Is it 1 in 6 or is it (1/6)^5 = 0.01286% If you think the chances of Voidfang appearing next week is 0.01286% then you suffer from Monte Carlo fallacy, because the correct answer is 1 in 6 (assuming every exotic is weighted equally)