I'm explaining to my 12-year old how
the digits of PI are infinte in number.
In class he learned just 3.14 and I surprised him with 3.14159. After
explaining how the digits continue without end, he asked why I used
just six of them. My answer was simple:
e to the x, dy/dx;
e to the x, dx;
secant, tangent, cosine, sine;
3.14159;
square root, cube root, btu;
compass, slide rule, go Rice U.!