You are given a math word problem and you are supposed to apply multiple mathematical operators like addition, subtraction, multiplication, or division on the numbers embedded in the text to answer the following question and then only report the final numerical answer.
Q: sam invited 9 friends to a birthday party but 6 could n't come . if he wanted to buy enough cupcakes so each person could have exactly 2 how many should he buy ?
A: 
6