Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| geohash length | lat bits | lng bits | lat error | lng error | km error |
| --- | --- | --- | --- | --- | --- |
| 1.0 | 2.0 | 3.0 | ±23 | ±23 | ±2500 |
| 2.0 | 5.0 | 5.0 | ± 2.8 | ± 5.6 | ±630 |
| 3.0 | 7.0 | 8.0 | ± 0.70 | ± 0.7 | ±78 |
| 4.0 | 10.0 | 10.0 | ± 0.087 | ± 0.18 | ±20 |
| 5.0 | 12.0 | 13.0 | ± 0.022 | ± 0.022 | ±2.4 |
| 6.0 | 15.0 | 15.0 | ± 0.0027 | ± 0.0055 | ±0.61 |
| 7.0 | 17.0 | 18.0 | ±0.00068 | ±0.00068 | ±0.076 |
| 8.0 | 20.0 | 20.0 | ±0.000085 | ±0.00017 | ±0.019 |
Question:
What is the lowest geohash length when the lat bits are less than 7, and the km error of ±2500?
Answer:
1.0