Circumference of a circle = diameter 3.1416

Diameter of a circle = circumference .31831

Area of a circle = the square of the diameter 0.7854

Surface of a ball (sphere) = the square of the diameter 3.1416

Side of a square inscribed in a circle = diameter 0.70711

Diameter of a circle to circumscribe a square = one side 1.4142

Cubic inches (volume) in a ball = cube of the diameter 0.5236

When doubled, the diameter of a pipe increases its capacity four times

Radius of a circle 6.283185 = circumference

Square of the circumference of a circle 0.07958 = area

1/2 circumference of a circle 1/2 its diameter = area

Circumference of a circle .159155 = radius

Square root of the area of a circle 0.56419 = radius

Square root of the area of a circle 1.12838 = diameter

AII-12