Save guides, add subjects and pick up where you left off with your BBC account. So, the number \(5.743\) is said to have 3 decimal places. The number \(5.1492\) has four decimal places, while \(4. ...

Using the formula C=2pir with fifteen decimal places of pi, you’d only be off on the true circumference of the circle by a centimeter or so. On solar scales, there’s no need to go further.

On Pi Day (March 14), NASA reminded us why we need only a small slice of the irrational number's infinite decimal places to explain most of the known universe.