I know you can add a loop cut using Ctrl+R, but I want to know how to specify how many to add, i.e. add 15 loop cuts to a plane. I know you can manually use the scroll wheel to get this number, however this can be quite tedious.
You can do this simply by typing the desired number (1 then 5) after pressing Ctrl+R and before left-clicking to complete the operation.
And for the sake of completeness:
You can also use the controls on the toolbar (T)
Or using F6 will bring a pop-up window with the tool's options: