Pi is an irrational number, meaning it has an infinite number of nonrepeating decimal places. But it turns out, NASA scientists need only a small slice of pi — the first 15 decimal places — to solve most of their math problems. And even when working out problems on the most mind-bending cosmic scales, they never need more than a few dozen extra digits.
We currently know the first 62.8 trillion digits of pi, thanks to a supercomputer that crunched the number for more than 100 days. But after that, pi's decimal places are a complete mystery to us. The reason scientists don't need to bother including any more digits in their calculations is that the numbers they are using, even at planetary or stellar scales, are too small for additional decimal places to have any real effect on the output value, according to NASA's Jet Propulsion Laboratory.Take our planet: Earth has a diameter of around 7,900 miles , which means its circumference is around 24,900 miles .