Norway uses the metric system of measurement. Most Norwegians don't know how to convert for instance between Centigrade and Fahrenheit, between kilometers and miles, or between meters and feet. Fuel efficiency of cars is indicated as "litres pr 10 kilometers", not as "miles per gallon".

Norwegians use comma as the decimal sign, for instance 12,000 means 12 (specified with three decimal places) not 12 thousand, whereas 12.000 means 12 thousand.

Norway uses central european time (one hour before London). Because Northern Norway stretches far east, sunrise is relatively early in Finnmark county.

Sunday  is regarded as the last day of the week. When weekdays are refered to by numbers (such as in ferry timetables), "1" means Monday. 

Norwegians use both 24 and 12 hour system, spoken often 12 hour system and 24 hour system in writing. Norwegians generally don't use PM/AM to indicate morning or afternoon. 

There is no concept of ground floor in Norwegian, the entrance level of a building is called first floor ("første etasje"). Elevators for instance will indicate ground floor as 1, and underground floors as U or -1 (minus 1).