This is the easiest way to install latest version of Opera browser to Ubuntu 9.10 Karmic Koala.
First of all make sure you have latest update of your Ubuntu.
Now, download Opera package from http://www.opera.com/browser/download/
Then, using Terminal, install libqt3-mt package using command “sudo apt-get install libqt3-mt”
Install Opera using command “sudo dpkg -i opera_10.10.4742.gcc4.qt3_i386.deb”
And your Opera browser ready to rock and roll!
NOTE: opera_10.10.4742.gcc4.qt3_i386.deb maybe different with your version.