Arithmetic Posted on 2nd November 201516th July 2021 by ThePD (The Project Definition) Arithmetic is a part of mathematics that involves the adding and multiplying, etc. of numbers. Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on LinkedIn (Opens in new window) Related Posted in Science and tagged mathematics. ThePD (The Project Definition) ThePD has been developing the Preferred Project Definitions based on the actual project execution and operation experiences and knowledge with the Project Language, and sharing with you daily basis.