The National Aeronautics and Space Administration (NASA) is a United States federal agency in the direction of science and technology in air and space. With the Soviet satellite Sputnik launch in 1957, the Space Age began. NASA was founded in 1958 and was established to supervise space exploration and aeronautics studies in the United States. But did you ever wonder how many decimals of pi does NASA use?

*When calculating interplanetary travel, NASA only considers the first 15 digits of pi. You could compute the circumference of a circle the size of the visible universe to an accuracy equal to the diameter of a hydrogen atom with a precision of 40 digits.*

**What is Pi? **

The lowercase Greek letter π sometimes spelled pi, is used by mathematicians to represent the ratio of a circle’s circumference to its diameter. It is derived from the initial letter of the Greek word *perimetros*, which means circumference.

The ratio of a circle’s circumference to its diameter is expressed as pi, which is written as the Greek letter for pi. This ratio will consistently equal pi, regardless of the size of the circle. (Source: Scientific American)

**What is the Purpose of Pi?**

Pi is used in fundamental mathematics to calculate the area and circumference. By multiplying the circle’s radius squared times pi, you can find the area. To determine the size of a circle with a radius of 3 centimeters, multiply 32 by 28.27 centimeters.

Pi is most often used in calculations involving circles. However, it is not only a number that connects circumference and diameter. Amazingly, it also relates the diameter or radius of a circle with the area of that circle by the formula: the area is equal to pi times the radius squared. Furthermore, pi appears frequently and surprisingly in a variety of mathematical contexts. (Source: Scientific American)

**Where Did Pi Come From? **

For about 4,000 years, the significance of pi has been known and utilized in different aspects of the academe. According to History, the Babylonians and Egyptians were aware of the existence and importance of the constant π. Knowing that every circle had the same circumference to diameter ratio.

They had imprecise numerical guesses for the value of pi, which subsequent mathematicians enhanced upon in ancient Greece, particularly Archimedes.

Archimedes of Syracuse was one of the greatest mathematicians of the ancient world and was the first to calculate pi. He approximated the area of a circle by utilizing the Pythagorean Theorem to find the areas of two regular polygons: the polygon inscribed within the circle and the polygon within which the circle was circumscribed.

On the other hand, Zu Chongzhi, a famous Chinese mathematician and astronomer, took a similar technique. He would not have been knowledgeable about Archimedes’ method, and nothing is known about his work due to the lack of access to literature on the subject.

By the 1700s, mathematicians began to use the Greek letter π. William Jones first used the symbol in 1706, and Leonhard Euler popularized it in 1737. (Source: Wired)