diff --git a/site-lisp/octal-to-hex.el b/site-lisp/octal-to-hex.el
index d433b43..562a03c 100644
--- a/site-lisp/octal-to-hex.el
+++ b/site-lisp/octal-to-hex.el
@@ -11,3 +11,29 @@
 	    (cl-map 'vector
 		    (lambda (c) (make-glyph-code c 'escape-glyph))
 		    (format "\\%02x" x)))))
+
+
+(defun use-octal-not-hex ()
+  "Use cctadecimal escape sequences instead of hex."
+  (interactive)
+  (require 'cl-lib)
+  (unless buffer-display-table
+    (setq buffer-display-table (make-display-table)))
+  (setq unprintable (append (number-sequence 127 255) (number-sequence 0 8) (number-sequence 11 31)))
+  (cl-loop
+   for x in unprintable
+   do (aset buffer-display-table (unibyte-char-to-multibyte x)
+	    (cl-map 'vector
+		    (lambda (c) (make-glyph-code c 'escape-glyph))
+		    (format "\\%0do" x)))))
+
+;; Hex string to dezimal
+(string-to-number "FF" 16) ;; => 255
+
+;; Hex string to dezimal
+(string-to-number "377" 8) ;; => 255
+
+;; Dezimal string to hex
+(format "%X" 255) ;; => "FF"
+
+(string-to-number "e001" 16)