9th day is the Answer.

1st Day- 1 Lotus

2nd Day- 2 Lotus

3rd Day- 4 Lotus

4th Day- 8 Lotus

5th Day- 16 Lotus

6th Day- 32 Lotus

7th Day- 64 Lotus

8th Day- 128 Lotus

9th Day- 256 Lotus

10th Day- 512 Lotus