If you want it to type: 1/25, simply click the Insert Page Number button,
then type "/" (the slash) and then click the Insert Number of Pages button.
If you want it to type: "Page 1 of 25" for instance: type the word "Page",
press the space bar once, click the Insert Page Number button, press the
space bar once, type "of", press the space bar once, and then click the
Insert Number of Pages button.