To change the units of measure in the rulers, choose Pages > Preferences, click Rulers, and choose an item from the Ruler Units pop-up menu.

To display measurements as a percentage of the distance across the page, choose Pages > Preferences, click Rulers, and then select “Display ruler units as percentage.”

To place the ruler’s horizontal origin point at the center of the page, choose Pages > Preferences, click Rulers, and then select “Place origin at center of ruler.”

To display the vertical ruler in a word processing document, choose Pages > Preferences, click Rulers, and then select “Enable vertical ruler in word processing documents.”