1. Navigation and Location Tracking: Pi is used to calculate distances between two points on the Earth's surface, such as the distance between two cities. It is also used in GPS systems to calculate location and track position.

2. Astronomy: Pi is used to calculate the circumference, area, and volume of celestial bodies such as planets, stars, and galaxies.

3. Engineering and Construction: Pi is used to calculate the dimensions of structures such as bridges and buildings, as well as to calculate the strength of materials used in construction.

4. Computer Science: Pi is used to calculate the area of a circle, which is used in computer graphics and animation.