Drop One Character

Your proximity search stores 7 character geohashes and someone proposes widening the search by matching on the first 6 characters instead. Here is the standard precision table for those two lengths.

length	latitude bits	longitude bits	latitude error	longitude error
6	15	15	±0.0027°	±0.0055°
7	17	18	±0.00068°	±0.00068°

Dropping the last character grows the cell by what factor in each direction?

Both directions grow by $\sqrt{32} \approx 5.7$ , so the area grows 32x.

Latitude grows 4x and longitude grows 8x, so the area grows 32x.

Latitude grows 8x and longitude grows 4x, so the area grows 32x.

Both directions grow 32x, so the area grows 1024x.