Firefox Shortcut for Tabs

I use Firefox as my browser, have for a while now, and I just finally learned a kewl trick with it. Did you know that you can get from one tab to the next by pressing Ctrl+1 or +2 or +3... The number pressed corresponds to the number of the tab you have open. counting from the left. I have no idea what happens if you have 10 or more tabs, but I usually have 4 or 6 open in a browser as I work on websites so this is a great way for me to quickly go from tab to tab.