If your presentation is long, but you still want to print handouts for your audience, add page numbers to your handouts to make it easier to follow along. You can do it in three quick steps.
Click Insert > Header & Footer.
In the Header and Footer box, click Notes and Handouts tab, check the Page number box.
Click Apply to All.
And presto — page numbers appear in the lower left corner of your slide handouts.
For more information about headers and footers in PowerPoint, see