Possessive apostrophes
This is a quick and no-thought-required way I’ve always used to check whether a possessive apostrophe’s in the right place. A possessive apostrophe can always be expressed without the apostrophe by flipping the order of the words and inserting “of” between them. For example, “Schapelle’s cannabis” can be rephrased as “the cannabis of Schapelle”. You can do this with any phrase to isolate the subject of the phrase and thus where the apostrophe should go. Some examples:
Where should the apostrophe go in, “She gave him 20 weeks notice“?
Rephrase as: She gave him notice of 20 weeks.
Insert apostrophe: 20 weeks’ notice.Where should the apostrophe go in, “You could see the whites of the dogs eyes“?
This can be rephrased in two ways. Either, “You could see the whites of the eyes of the dog“, or, “You could see the whites of the eyes of the dogs“.
It becomes clearer which one is appropriate. If you’re about to be mauled by one dog, the former applies and the phrase should be “the dog’s eyes”. If you’re about to be mauled by a pack of dogs, the latter applies and the phrase should be “the dogs’ eyes”.Where should the apostrophe go in, “Bob was thrown out of the womens toilets“?
Rephrase as: Bob was thrown out of the toilets of the women.
Insert apostrophe: women’s toilets.
The only exception is when you’re using “its” in a possessive sense. No apostrophe is used. For example, “its stomach”.
12:34pm (GMT +11.00) tomorrow 
