Norway is expensive
The Norwegian Krone is the currency used in Norway. So, if all you have is Euro, you won't get very far. Because the Norwegian Krone has lately depreciated, traveling to Norway in the near future will be less expensive than it was only a year ago.
It should be noted that Norway is becoming increasingly cashless. A credit card can be used for almost anything, even cabs and hot dogs! That means that forgetting to carry cash isn't a big deal.
Despite the fact that the Norwegian Krone is now weaker, Norway remains an expensive country in comparison to the rest of Europe. If you plan to eat out, your bill will almost certainly be more than if you ate at home. You'll want to leave some extra money in your budget for food and other expenses.
Eating supermarket food is a good method to keep prices down. In Norway, eating out is not a popular pastime, owing to the high expense of food. Buy some supplies from a grocery shop and cook your own meals for a true local experience.