How do you know that clicking on an item in a menu will display a submenu? the item has a dot in front of it. the item is followed by an arrow. the item is followed by three dots. the item is gray.

The item is followed by three dots.

Generally, especially inside web browsers (such as chrome, IE, etc), they will have three dots vertically down. This is the menu that will display groups of submenu's (such as history, bookmarks, etc) as well as other tools that can be used.

hope this helps

According to my brain it's a rational number because it can be put as a fraction