Helpful Hints 
Additional Helpful Data 
To find
circumference of a circle, multiply diameter by 3.1416. 

To
find diameter of a circle, multiply circumference by .31831. 
To find area
of a circle, multiply square of diameter by 0.7854. 
Area of a rectangle
= length multiplied by breadth. Doubling the diameter of a circle
increases its area four times. 
To find area of a triangle, multiply
base by 1/222 perpendicular height. 
Area of ellipse
= product of both diameters times 0.7854. 
Area of parallelogram = base times
altitude. 
To find side of an inscribed
square, multiply diameter by 0.7071 or multiply circumference
by 0.2251 or divide circumference by 4.4428. 
Side of an inscribed cube = radius
of sphere times 1.1547. 
To find side of an equal
square, multiply diameter by .8861 Square. A side multiplied
by 14142 equals diameter of its circumscribing circle. 
A side multiplied by 1.128 equals diameter
of an equal circle. 
A side multiplied by 3.547 equals
circumference of an equal circle. 
To find cubic inches in a ball, multiply
cube of diameter by .5236. 
To find cubic contents of
a cone, multiply area of base by 1/3 the altitude. 
Surface of frustrum of cone or pyramid
= sum of circumference of both ends and get square root. Add the 2
areas and multiply 1/3 altitude. 
Doubling the diameter of
a pipe increases its capacity four times. 
A gallon of water (U.S. standard)
weighs 8 1/3 lbs. and contains 231 cubic inches. 
A cubic foot of water
contains 7 1/2 gallons, 1728 cubic inches, and weighs 62 1/2 lbs. 
To find the pressure in pounds per square inch
of a column of water, multiply the height of the column in
feet by .434. 
To find capacity of tanks
any size, given dimensions of a cylinder in inches, to find its capacity
in U.S. gallons: square the diameter, multiply by the length and by
.0034. 
