Here it is...

- The symbols for each number change each time.

- The only answers you can get are multiples of 9 (unless you screw up).

- All numbers divisible by nine have the same symbol as eachother.

- They show you the symbol for the numbers divisible by 9 (which will be different each time) and you go "oh my gosh, that's so cool!"

- I didn't figure this out by myself, I just confirmed it.

It's still pretty cool though.