...are a god send!
If you have them, you can easily turn boring worksheets into games. Or even simpler, hang the answer key up and let students self monitor their work so you can spend time addressing real questions.
I have turned many a worksheet into a pong game by merely snipping the problem and answer and pasting into a powerpoint.
And of course, it's always helpful to have answer keys for assessments already made.
I have been collecting paper answer keys all year and one of my projects for this summer is to make sure I have a digital version for each one. Even if they are just handwritten, scanning them provides the option to snip and paste those answers wherever I would like. I'm sure this would also come in handy for QR codes and even Kahoot. Kuta is great for this depending on the question type you are looking for.
Such an easy task that can pay off big for you in the long run. Copy and paste are a teacher's best friend.
Not to mention it is great for other teachers when you share a file with an answer key included. =)