Name of Norwegian Currency is the ´Norwegian Krone (NOK), represented either as NOK (preceding the number), Nrk (preceding the number) or simply KR (following the amount).
One Norwegian Krone is equal to 100 øre. Coins come in denominations of 50 øre, NOK 1, NOK 5, NOK 10 and NOK 20, and notes come in denomination of NOK 50, NOK 100, NOK 200, NOK 500 and NOK 1000.
Norway is using less and less cash. That means that it's not a crisis if you forgot to bring cash, because it is possible to buy almost anything with a credit card.
Visa and MasterCard are the most commonly accepted credit cards, with far fewer accepting Amex or Diners. Some supermarkets do not accept foreign credit cards, although
In Norway for the most part tipping is not common. In restaurants and bars can be exceptions where you can tip if you are happy with the service and the food. It is up to you how much to tip, but normally you give 5-15 % of the total amount of the bill.
In Norway, the easiest way to change money are banks near tourist information centres. There are some places, however, the only way to exchange money is at post offices, where the exchange fee might be as high as NOK 75 (approx. €9.50 or $12.20 USD).
You can see current conversion rates here