Chirality and number of sterioisomers I have recently read that the number of sterioisomers in a compound having n chiral centres is 2^n. (That is, if no meso form is present)

The below question asks for the number of sterioisomers in the product obtained. And the product obtained has 3chiral centres, so it should be 2^3=8, but the answer given is two. 
There is no plane of symmetry.

Do I not consider the carbon attached to the benzene ring when looking for chirality? 

Could someone help me out? 
Question attached. 
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I believe you are misreading the question. Rather than asking for the number of stereoisomers the product can have (this is where 2^n comes in), it is asking for the number of stereoisomeric products formed. Note that that the two products are diastereomers, which is a type of stereoisomeric relationship. It's not looking for any fancy calculation; just for the related products.

In a Gringard mechanims, the Gringard reagent can attack the carbonyl on either the re or si face, which in turn, can yield an R chiral center or an S center at the location of attack. This lends to the diastereotpic products.