Is pi a constant?
Tuesday, November 18th, 2008- Did you know that the ratio of the cicumference and the diameter of a circle equals 3.14159… , or pi amongst friends.
- Which circle?
- Any circle.
- You mean the ratio does not change when you move from a tiny circle to a really big circle.
- Yep.
- I find that hard to believe.
- There is a simple explanation.
- I find that even harder to believe.
- Here is something more innocent to think about.
- I am all ears.
- How many pis are needed to express the first ten natural numbers?
- You mean 1 to 10?
- Yes.
- Please explain.
- You are only allowed to use pi, addition, multiplication, parentheses, square root (sqrt), and the greatest integer function ([ ]).
- What is [pi]?
- Since [n] is the largest integer less than or equal to n, [pi] = 3.
- And I can’t use division, subtraction, or digits?
- That’s right.
- I believe I can do all the numbers from 1 to 10 using less than fifty pis.
- How many less?
Problem source: Dan’s problem archives.









