I often see activities like this where a student is working independently to match numbers. I've used a few of them myself. However, there have been times when I've noticed a child put the wrong answer on top, and unless it's brought to my attention, it doesn't get corrected.
My suggestion is this. At the bottom inside the cup, put the same number of dots. That way, when the child mentions s/he's done, you can turn the cup over and have them check to see if their answers are correct.
On activities like this, there has to be a way for them to check their answers to make sure they're actually counting correctly and not just putting down any answer for the sake of finishing the job.