Take a look at this picture:
I want the dropdown menu items to be stack from left to right (horizontally). I cannot seem get this to work, tried using \"l
Enclose those li into a ul list and the class as list-inline like this
Check this screenshot

Here is the JSFiddle
Updates1:
As I mentioned in comments, class: dropdown-menu has the min-width as 160px. Hence it is fixed to width. Try to override it.

Updates2:
As I mentioned in comments, bootstrap has some default style which can be overridden like
.dropdown-menu{
min-width: 200px;
}
Incase if you feel that it affects other elements then override using id selector.
#Numberlist.dropdown-menu{
min-width: 200px;
}
Find the difference in this JSFiddle