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