No ‘S’ on the word ‘euro’ on the new €50 note?

In fact, no, it is not – in ordinary writing you would write, for example, ‘pouvez-vous me prêter dix euros?' (can you lend me ten euros).

So why is there is no ‘S’ on the word on banknotes? In fact this applies to all of them and not just the new €50 ones: eg. 10 euro, 20 euro, as well as on coins: 1 euro, 2 euro.

Smaller coins also use the singular, for example: 50 euro cent. This is despite the fact that when France changed to the euro from the French franc the French government recommended continuing to use the word centime so as to avoid confusion with cent meaning the number 100.

British notes and coins on the other hand always add an ‘S’: 10 pounds, two pounds.

In fact the reason for using an invariable singular on euro notes and coins is a practical one: Banque de France says it is because they have to circulate through the EU countries and their languages have different rules for the plural of words.