This question already has an answer here:
When someone has more than one master’s degree, should these be described as have several masters’ degrees or several master’s degrees?
In other words, which of these two applies:
- (singular) a master’s degree > (plural) several master’s degrees
- (singular) a master’s degree > (plural) several masters’ degrees
Please note that this is a different question from what this has been marked as a duplicate of. That addresses the question for the singular. This question is about the plural case. There is definitely an apostrophe, but the question is where it should go.