9.6 Plurals of Symbols, Letters, Numbers, and Years.

Use 's to indicate the plural of letters, signs, or symbols spoken as such, or for words referred to as words when s alone would be confusing. Note the use of italics with the inflectional ending in roman type for words, letters, and numbers but not for symbols and signs. (See also , Punctuation, Apostrophe, Using Apostrophes to Form Plurals.)He uses too many and's. All of the capital P’s should be underlined. Please use +’s to indicate a positive result. Note: If the symbol can be easily expressed using words, this is preferred: Please use plus signs to indicate positive ...Less