The other day I came across a story that included the following line:

I had never encountered the word на́дцатый before, but instinct immediately told me it meant ‘umpteenth.’ Instincts always have to be double checked when you are dealing with a language not native to you, so I consulted a dictionary and found confirmation; and to my shock I also found out that there is a number ‘umpteen,’ which is на́дцать. That is very cool. These words are jocular, of course, not something you would write in a professional document or presentation, but everyone understands them. The noun form declines like this:

and the adjective form declines like a standard adjective:

Remember that these words are slightly humorous, so you will see them in informal contexts. Here are some theoretically possible sample sentences.

Here's the whole story I mentioned before (source). Enjoy!