A new fast food restaurant opened 5 months ago. The table belows shows the number of burgers they've sold so far.
| Month | Burgers Sold |
| 1 | 3,446 |
| 2 | 2,609 |
| 3 | 3,436 |
| 4 | 2,529 |
| 5 | 1,649 |
| 13,669 |
The next month (after spending some money on an ad) they sold 9 times as many as they had sold in the previous 5 months. How many more burgers did they sell after running the ad?