Can you answer without googling? I asked at least 5 people that question today, all with graduate degrees, and all answered 7. That is wrong.
Apparently the answer isn't 4, either. Although it was when I grew up. We had the Arctic, Indian, Atlantic and Pacific oceans. But wait...in 2000 the powers that be (who exactly gets to decide these things?) decided there should be another ocean. So now we have 5 oceans (or one ocean divided into 5 zones), the fifth being the Southern Ocean.
WTF? Why have I not head about this before now? And how the hell do you just get to up and create a new ocean? Is this to make up for the deplanetization of Pluto? Because it's not the same, dudes, and Pluto will always be a planet in my heart.