PI()

Syntax. PI()

Definition. This function returns the constant pi (π=3.14159265358979) accurate to 15 digits.

Arguments. None

Background. Pi (π) defines the ratio of the circumference of a circle to its diameter (d) or radius (r):

dπ = c

or

2r π = c

c is the circumference of the circle, and π is an infinite number that can only be approximated. Excel uses 15 decimal places. Rounded to 100 decimal places, π has the following value:

3.141 592 653 589 793 238 462 643 383 279 502 884 197 169 399 375 105 820 974 944 592 307 816 406 286 208 998 628 034 825 342 117 067 0

Examples. Pi is used for calculating circles:

  • In geometry:

    • Cylinder volume (r = radius, h = height) V = r 2 πh

    • Surface area of a sphere (r = radius) A0= 4πr 2

  • In arithmetic:

    • Euler’s constant e

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