OK, I am no statistician, but the first comment was right - it's about getting two calls to any one street. I think that getting 2 consecutive calls to one particular street is 1 in 2717. And getting 3 consecutive calls to that street would be 1 in 2717 times 1 in 2717. But in your case they weren't consecutive, so the odds have to be lower. I leave it to a real statistician to take it further. Office worker.