all European union countries use the euro as their currency
This statement is not entirely accurate. While most European Union (EU) countries use the euro as their currency, there are a few exceptions.
As of September 2021, 19 out of the 27 EU member countries use the euro as their official currency. These countries are Austria, Belgium, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Portugal, Slovakia, Slovenia, and Spain.
The remaining eight EU member countries do not use the euro as their currency. These countries are Bulgaria, Croatia, the Czech Republic, Denmark, Hungary, Poland, Romania, and Sweden. Each of these nations has its own currency.
It's worth mentioning that some EU countries have committed to adopting the euro in the future, but have not yet done so, while others have no plans to join the eurozone. Overall, the euro is the most widely used currency within the EU, but not all EU countries have adopted it.