Here are the rules that will apply: Rule one: If possessive noun is singular, then you need to add apostrophe plus “s”. Rule two: If possessive noun is not ending with the letter “s”, then you always need to add apostrophe plus “s”. Rule three: If possessive noun ends with the “s” and it is plural, what you only need to do is to add apostrophe.

To show possession using an apostrophe, add ’s for individuals (“Smith’s car”) and just the apostrophe after the s for plurals (“the Smiths’ car,” “the Martinezes’ dog”). By convention, names from classical mythology and the Bible ending in s show possession with the apostrophe only (“Jesus’ teachings”).

Once you've determined whether you need to make a possessive, follow these rules to create one. add 's to the singular form of the word (even if it ends in -s): the owner's car James's hat (James' hat is also acceptable. For plural, proper nouns that are possessive, use an apostrophe after the 's': "The Eggleses' presentation was good."

The apostrophe has three uses: 1) to form possessive nouns; 2) to show the omission of letters; and 3) to indicate plurals of letters, numbers, and symbols. Do not use apostrophes to form possessive pronouns (i.e. his/her computer) or noun plurals that are not possessives.