Practicing while looking at screen/page or not?

I’m up to chapter 10 in the book and am enjoying it so far. However, when I got to chapter 9, I started to wonder if I’m practicing incorrectly by staring at the screen while solving problems. Being able to see the problem while solving it eliminates the need for me to memorize the original problem numbers, which makes it easier. But now I’m questioning whether I should look away from the screen/page while solving problems to truly gain mastery. What do you all do, and what are your thoughts on this?