Is Associativity a Problem?

So here the condition is that a times a equals e Then what then what right? So now can we fill this out? Can we fill in the remaining two by two part? I put in everything below e and a and across from e and a Because of those were determined I have to get one of every letter in every row in every column Sudoku rule And then what do I do in this last part? You just have a's and e's left. I have as and e's so we can make b times b equal a And then that will decide everything else Or we can makeb times b equal the e And that will also decide everything else Like the e's could just