"Pi" π is a number
No matter how big your circle, the ratio of circumference to diameter is the value of Pi.
A pi is an irrational number you can't write it down as a non-infinite decimal.
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Definition: Pi is a number - approximately 3.14159 - It is the circumference of any circle divided by its diameter.
Some people have written computer programs and calculated it to astonishing accuracy. Here is a web site that has it to 200 million digits:
Pi to a few dozen digits
3.14159265358979323846264338327950288419716939937510582097494459230
7816406286208998628034825342117067982148086513282306647093844609550
5822317253594081284811174502841027019385211055596446229489549303819
6442881097566593344612847564823378678316527120190914564856692346034
8610454326648213393607260249141273724587006606315588174881520920962
829254091715364367892590360011330530548820466521384146951941511609...
On your calculator
Most calculators have a button to enter the value of Pi directly, so you don't usually have to remember all the digits. But it's handy to remember pi = 3.14159 anyway. Using the calculator Pi button is better because it inputs Pi to the most number of decimal places that the calculator is capable of.Approximating Pi
If you just need a rough value for Pi you can assume it is 22/7, but this is only accurate to two decimal places. However, it may be accurate enough for some uses when you don't have a calculator handy.An even more accurate approximation is 355/113. This is correct to 6 decimal places.
