Here's the definition of sudoku in Wikipedia:
How should one read 9×9の or 3×3の out loud?
I think you're asking this because in English, we distinguish times from by:
But I think in Japanese, it's just かける in both cases:
You can see that both uses are listed on Wikipedia's article for
This ALC example also uses かける to correspond to English by, although this example has units:
I also found some videos online where
So I think you can just say "number かける number".