Apostrophes plurals

Possessive plural nouns already ending in 5 need only the apostrophe added ... 

Rule 10 Form the plural of multiple-letter, all-capital abbreviations and abbreviations ending in a capital letter by adding a lowercase s only. Do not put an apostrophe before the s do not add an s to units of measure ... 

Apostrophes are used to form contractions, indicate ownership, and form certain plurals. Review these six rules for their use. 

CEO s needs an apostrophe to show possession, accounts does not need an apostrophe (it is merely plural), and companies is not plural but singular, and also needs an apostrophe to show possession. The only choice that corrects all three errors is e. 

Form the possessive of plural nouns that do not end in s by adding an apostrophe and an s . Form the possessive of plural nouns that end in s by adding an apostrophe only. 

To avoid ambiguity or poor appearance, add an apostrophe and a lowercase s to form the plurals of lowercase abbreviations, single-capital-letter abbreviations, abbreviations ending in a subscript or superscript, and abbreviations ending in an italic letter. 

Use numerals for decades, and form their plurals by adding an s . Do not use apostrophes in any position. 

When numerals are used as names and not enumerators, form their plurals by adding an apostrophe and s to avoid confusion with mathematical expressions and to make it clear that the s is not part of the name. 

Form the plurals of mathematical symbols by adding an apostrophe and s if you cannot use a word such as values or levels . 

Add only an apostrophe to a plural noun ending in s to show possession. 

To avoid confusion, you may use an apostrophe plus s to form the plurals of letters, figures, and words discussed as words no apostrophe is also acceptable. 

The apostrophe is one of the most commonly misused punctuation marks, but there are only two uses for apostrophes— to show possession and to make a contraction. Never ever use an apostrophe to make a word plural. About contractions. . . ... 

Forming the plural of all-capital abbreviations. Add a lowercase s only, with no apostrophe. 

What can seem confusing is the fact that with other words ending in s we often use an apostrophe to indicate possession (bird s nest). The apostrophe in this case is being used instead of saying the nest of the bird it is a kind of shorthand. The apostrophe placed before the final s is the singular possessive form (bird s nest) and the apostrophe placed after the s is the plural possessive form (birds nests). 

Also remember to look out for the situations when you do not use an apostrophe, when nouns are being used in their plural form ... 

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