Hello, We are all familiar with the formula that relates union of 2 mutually NOT exclusive events formula: [itex] P(A\cup B)=P(A)+P(B)-P(A\cap B) [/itex] For 3 sets its easily derived using this formula. But I wanted to take this step further. I wanted to find a general formula, that represents union of n elements. I don't know how to write that In LaTex. If anybody knows the answer, please don't tell me. Tell me some guidelines to solution. I have tried, but I get stuck with recursive sums, and I can't get out of them.