Luke started working on a 1000-piece jigsaw puzzle. The first day he worked on it, he put together 10% of the pieces. On the second day, he put together another 20% of the remaining pieces from the first day. On the third day, he put together 30% of the remaining pieces from the previous day. How many pieces does he have left to complete after the third day? Think carefully first, then make a decision:
Luke started putting together, 1000 x 0.1 = 100 pieces. The next day, there were 1000 - 100 = 900 pieces left. Then he put together 900 * 0.2 = 180 pieces on the second day. So there were 900 - 180 = 720 pieces left. On the third day, he put together 720 * 0.3 = 216 pieces. Therefore, Luke still has 720 - 216 = 504 pieces left to complete the puzzle. So, the answer is 504.