Can someone please verify that I've got my head on straight and see if I've got the right answer to the following probability calculation...

Three completely unrelated events have the following probabilities...

A has a probability of 0.14
B has a probability of 0.47
C has a probability of 0.71

What is the probability of 1 OR MORE of those events happening?

My working so far is to rewrite the expression as ((A or B) or C) ...

OR is calculated for 2 independent events thus: (a+b)-(a*b)

Therefore for (A or B or C)...
probtemp = ((A+B)-(A*B))
probtemp = (probtemp+C)-(probtemp*C)

For which I get a final answer of 0.867818.

This isn't very elegant really, assuming this is the right result, is there a nicer way to calculate OR probabilities for a list of events (eg without having to iterate through an array, acumulating the probability as I go)?

The internet really doesn't do a good job of explaining this kind of thing, not taht i've seen anyway, does anyone know any good online resources for probability math?