Since I’m here, I notice very quickly that smaller bank notes are damn fucking rare in Hungary and the cashier almost every time argue with you if you want to pay your buyings with a 10k or 20k bank note (What is understandable!). Unfortunately, you can’t choose any denomination of different bank notes when you withdraw money.
To avoid those issues, I recommend withdrawing odd amounts like 2.9K, 4.9K, 8.9K, etc. because here you will get (in almost every case) one 5k and four 1k notes with whom you can survive a good while.
I made some excellent experiences during the week and in the morning paying smaller amounts (around 1-1.5k with a 10k bank note in drugstores and supermarkets. During the noon and afternoon, they are allowed to reject bigger bank notes because they need the change.