The next time you must write a formal paper, make certain you have the correct style guide to use when creating the document. Some style manuals want you to write out "percent" after a number, and others may prefer that you use the percentage symbol instead. If you don't follow the manual's specific guidelines, you may end up wasting all your efforts. Colleges, journalism outlets, book publishers and scientific groups – to name a few – all use different style guides for writing.

Style guides or manuals, depending on the specific publication, provide the correct font to use; citation styles for citing books; article title and footnote formats; address and decimal formats; correct usage of em or en dashes, acronyms, numbers and percentages; quotation attribution requirements; and much more. Each style manual or guide is different and may have you write out the word "percent" or use the percentage symbol after the number.

Use the style guide best suited to your formal paper:

• Humanities studies typically use the MLA style manual. * Education and psychology use the APA style guide. * History, business and some fine arts studies use the Chicago-Turabian style guide. * Sciencing and engineering studies typically use the CSE-CBE style manual. * Book publishers prefer the Chicago Manual of Style
• Most journalism outlets use the AP style guide

Under the MLA style guide, write numbers out and add the word "percent" behind the number. For scientific papers, you can use the percent symbol, but check the guide you're using to ensure this is correct. The reason these guides require percent spelled out instead of using the symbol is to ensure no mistake is made. Symbols sometimes lead to confusion when used, unless required by the specific guide. The APA style guide requires the use of the percentage symbol after a number, but it also requires you to spell out percentages when using the word in a sentence.

For instance, in the APA style guide, you must format pages with 1-inch margins all around, include a header on each page called a running head – the title of your paper not to exceed 50 characters – and include four major sections in the paper such as:

• Title Page
  
• Abstract
  
• Main Body
  
• References

If you are writing a formal paper for a college course, the instructor will inform you, at some point, as to the correct style guide to use.