In Denmark you will have to face the fact that despite being a member of the EU zone since 1979, it still has its local currency, Danish krone, not euro. This is related to two factors: according to the constitution of 1953, only the royal house is entitled to print the Danish money. Therefore, transiting to euro they would have to change the constitution. The second factor is that the Danes convincingly voted against the introduction of euro as the main currency at the referendum in 2000. Therefore, it can be easily proclaimed that the Danish people prefer their own currency, Danish krones, but euros are accepted in most tourist places. If you do not want to worry about exchange rate you can use your credit card, which will be accepted everywhere.
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