What does it mean to beat the odds by X percent?

My first thought is that it means that the number of successes is (1+X) * the expected number of successes. If so, then beating a single 1-in-a-million shot means having 1 success where 1/1000000 success is expected, then X is 99999900 percent. That's an awful lot more than 29.2%. It's also strange because the exact number is affected by adding additional missions with 100% survivability--if you have 100 missions, one of which is 1 in a million odds and the rest of which are certain, and you beat them all, the number of successes is 100 while the expected number is 99.000001, and you only beat the odds by about 1%.