It would be good to introduce the word "Rakhunok" in context or in a photo before asking us what it means.
Why is "check" without article? Can I use, for example, article "the" in this case?
"The check", "check", "the bill" and "bill" are all accepted. Most likely you were marked wrong for some other mistake. Unfortunately, I can't tell you now, because I don't know what your input was. Next time just provide your full input without assuming what was wrong, so I can take a look and help.