Are you are using a US Keyboard and you wonder how can you write down the euro or pound symbol? Easy peasy… once you know how.
First of all we need to know what key is the compose key in our distro. Generally is the right “windows” key. You can search the internet for you specific distro typing <distro_name> compose key. For Ubuntu: https://help.ubuntu.com/community/ComposeKey
Now that you know what's your compose key you can use it this way Compose + e + = (you'll get the €)
Compose + l + = (you'll get the £)
You can also use E or L (uppercase)