Try a dollar sign in the replacement pattern ($1), instead of a backslash (\1). The backslash version (\1) is only for when you want a backreference inside the search pattern.
So, your replacement pattern should be 2$1.
Try a dollar sign in the replacement pattern ($1), instead of a backslash (\1). The backslash version (\1) is only for when you want a backreference inside the search pattern.
So, your replacement pattern should be 2$1.