How to type an en dash on Ubuntu 14.04
How can I type an en dash?
On OS X, I can type Alt + - (hyphen). On Windows, I can type Alt+0150.
If you're not familiar with the different types of dashes, you can read about them here.
You have to press Ctrl + Shift + u (for Unicode characters) then add the respective hexadecimal number of your symbol, which you can get from the Character Map (gucharmap) and press enter. In your case this would be 2013 or 2010.
Compose+--. is the fastest way.