164272

I added the numbers diagonally such as 1+30, 3 + 28, 5 + 26, 7 + 24 each answer is always 31. When I added the opposite numbers diagonally 2 + 20, 4 + 27, 6 + 25 each answer is also always 31.
I think this happens because the bottom line of numbers is decreasing and the top line is increasing and that keeps the answers even. I noticed that the street numbers I used go up to 30 and my answer is always 1 more than that.