Don't know how to call the police in Bulgaria? Wouldn't know which number to use for the fire brigade in France?
European MPs are this week reminding people they only need to remember one number when travelling in the EU.
The free emergency number 112 is common to all 27 member states - including the UK - and connects to ambulance, fire or police.
It has been in use for 20 years, but research has shown only one in four people knows about the number.
South East MEP Catherine Bearder said: "Every year 150 million people travel around the EU, they should all know about 112.
"We can get children to remember it too by saying: one mouth, one nose and two eyes."
Saturday, February 11, is the EU's 112 day, aimed at raising awareness of the anytime, anywhere number.