When you are measuring for print communication creation, it is sometimes difficult to deal with the fractions of inches.
Graphic designers use the pica as the basic measurement because, for one reason, it is a much smaller measure and is easier to work with.
This PDF explains it for you.
The Adobe design programs as well as MS Publisher have the option for you to set your measurements in picas instead of inches. In all of my examples in the PDFs from my basic design book, the "p" measurement refers to picas.
You can buy pica rulers either at art supply stores or online, just Google "pica" and a number of online stores will come up.
To download the PDF, click here or on the image.