Tanya went to the grocery store to buy some fruit. She bought 6 pears, 4 Granny Smith apples, 2 pineapples, and a small basket of plums, which were all placed in a single paper bag. Unfortunately, the bag that the fruit had been placed in had developed a hole. Therefore, as Tanya walked home, half of the fruit fell out of the bag. When she later counted the fruit left in the bag, there were only 9 pieces remaining. How many plums did she buy? Let's think first. Chain of thought:
If half of the fruit equals 9 pieces, then Tanya bought 2 * 9 = 18 pieces of fruit. Thus, Tanya bought 18 - 6 - 4 - 2 = 6 plums.
Therefore, the answer is 6.