Emacs functions to insert \sfrac{n}{m}

gistfile1.el

(defun insert-half ()
  "Insert '\sfrac{1}{2} '"
  (interactive)
  (insert "\\sfrac{1}{2} "))
(defun insert-third ()
  "Insert '\sfrac{1}{3} '"
  (interactive)
  (insert "\\sfrac{1}{3} "))
(defun insert-quarter ()
  "Insert '\sfrac{1}{4} '"
  (interactive)
  (insert "\\sfrac{1}{4} "))

(global-set-key (kbd "C-c 2") 'insert-half)
(global-set-key (kbd "C-c 3") 'insert-third)
(global-set-key (kbd "C-c 4") 'insert-quarter)