I've produced a sum total of 512 several times and that didn't work. I got a 512 square twice and that didn't work.

I'm using Ubuntu 16.04.1 with the Chromium browser.

I am tired of doing this puzzle and having anything resembling a logical answer being rejected.

I can confirm that you need to get the tile with 512 to get the silver key. Once you have one 512 tile, you should be able to check your solution and get the key.

The sum method I believe came about because people were confused by the game.

As I tiredly tried to explain last night, I got the 512 tile in two separate attempts and it didn't accept it. I suspect the problem is a glitch in Ubuntu Chromium itself and that if I had chosen to use FireFox instead, it probably would have worked. While Chromium may be the package Chrome is built from, Ubuntu's Chromium is usually a few iterations back.