Fiona Fang Baili is a circular space with a point as the center and a radius of Baili. It is usually used as a functional word to describe a large area. "Li" is also a household registration unit in the pre-Qin period, and about a hundred Li is one hundred such household registration units.

Mathematically speaking, one mile = 0.5km = 500m, and Fiona Fang thyme is the area of a circle with a radius of 50,000m. The area of a circle can be calculated as π×50000m? =2500000000π≈785398 1634m？ ≈7853Km？ .