Pi is an irrational number. It cannot be written a/b where a and b are integers.

Irrational numbers go on forever and never repeat, so writing them as numbers is not possible, just like sqrt(2), sqrt(3), e, and very many other numbers.

Pi is also a transendental number, as it is not a solution to a polynomial with integer coefficients.

If you were asking if there is a formula for pi, yes there are many.

One of the simplilest is

pi = 4(1-1/3+1/5-1/7+1/9-1/11...) Unfortunately it takes a lot of work to get each digit. There are many more formulas. See the reference.

If you were asking what to use when you see pi in a calculation: Pi is generally given a key on any scientific calculator look for `pi` .

Pi can be approximated by 22/7 which was first found by Archimedes who lived 287-212 BCE.

Pi can be approximated by 3.141592653589...

It has been computed to 2.7 trillion digits.

I would say either memorizing it, I know it to 13 digits, or using 22/7 (3.142).

If you were asking if there is a formula for pi, yes there are many.

One of the simplilest is

pi = 4(1-1/3+1/5-1/7+1/9-1/11...) Unfortunately it takes a lot of work to get each digit. There are many more formulas. See the reference.