PI
Applies to: 
Calculated column
Calculated table
Measure
Visual calculation
Returns the value of Pi, 3.14159265358979, accurate to 15 digits.
Syntax
PI()
Return value
A decimal number with the value of Pi, 3.14159265358979, accurate to 15 digits.
Remarks
Pi is a mathematical constant. In DAX, Pi is represented as a real number accurate to 15 digits, the same as Excel.
Example
The following formula calculates the area of a circle given the radius in the column, [Radius].
= PI()*([Radius]*2)