Writers use footnotes & endnotes in documents to explain, comment on or provide reference to something. Usually Footnotes appears at the bottom of the page and it contains extra information, clarification while Endnotes appears at the bottom of the document or section and it consist on some reference or citation.
A formula is simply a mathematical expression that uses numbers, cell references or both. A formula can use only numbers but in Excel most formulas you build will contain at least some references to others cells containing some numerical values.
PowerPoint provides to users a different and nifty option that is Smart Art. It a feature that helps us to add graphic in predefined layout. By using this we can insert different type of useful diagrams to our slides. With Smart Art you can create lists, process, cycle, hierarchy, relationship, pyramids and picture diagrams etc.