For JPL’s highest accuracy calculations, which are for interplanetary navigation, we use 3.141592653589793
by cutting pi off at the 15th decimal point… our calculated circumference of the 25 billion mile diameter circle would be wrong by 1.5 inches.
with our planet Earth, It would be off by the size of a molecule - How many decimals of pi do we need? / nasa-jpl

• Heron’s formula: What is the hidden meaning of 1 + 2 + 3 = 1 x 2 x 3 ?