3 months' or 3 month's

[jasonlulu_2000]

I saw an ad in a newspaper:
To celebrate the opening of our new fitness suite, get 3 month's membership for just ￡10 when you sign up for a minimum of 6 months, but be quick—this offer is only valid THIS MONTH. This amazing deal gives you free access to the gym, pool and sauna between 7a.m. and 10 p.m., and access to our fitness classes at just ￡1 per session (standard non-member fee ￡5).Don't miss out—sign up today!

I think "3 months' " is correct.

Am I right?

Thank a native teacher for help!

Jason

 

[Rover_KE]

You're right.

 

[Tdol]

Apostrophe abuse is not unknown among native speakers- you will see them used in plurals for no reason, a phenomenon known as the grocer's, possibly grocers', apostrophe.

 

[GoesStation]

Apostrophe abuse is not unknown among native speakers- you will see them used in plurals for no reason, a phenomenon known as the grocer's, possibly grocers', apostrophe.

It's their apostrophe. They evidently feel they can use it as they like.

 

[Tdol]

It was always the grocer's apostrophe, until an apostrophe zealot pointed out that it could be a case for the plural.

 

[Rover_KE]

It's the greengrocers apostrophe for me.

Prepare to cringe before clicking here.

 

[Tdol]

Greengrocer apostrophe would solve the problem.