Gillian and Char’s question: “What are the rules today to indicate a plural possessive (e.g., six hats that belong to girls)? We have come across situations where the apostrophe is left out or appears before the ‘s’ in girls, e.g., “six girl’s hats.” Which is correct?”
BizWritingTip response: First, you are right. “Six girl’s hats” is incorrect and confusing. Because we are talking about a number of hats — six to be exact— “girls” must be plural.
Now here’s the fun part. Do you add an apostrophe or not? Yes, if you wish to indicate possession, you add an apostrophe. If you place the apostrophe outside the “s,” then you make the word plural: girls’. If you place the apostrophe inside the “s,” the word is singular: girl’s.
Six girls’ hats are in the lost-and-found box. (Six hats belonging to girls are in the lost and found.)
A girl’s hat is in the lost and found. (One hat belonging to one girl is in the lost and found.)
However, if you wish to indicate that the hats are designed for girls – they don’t belong to anyone – do not use an apostrophe.
We sold six girls hats today. (Six hats for girls were sold.)
Often, the choice is going to be the writer’s decision. Remember, add the apostrophe to indicate possession. Omit the apostrophe if you can mentally insert the word “for.”