| Area of triangle = base X half the perpendicular height. |
| Area of circle = dia.2 X 0.7854. |
| Circum. of circle = dia. X 3.14159. |
| Circum. of circle X .31831 = the dia. |
| Dia. of circle X .8862 = the side of an equal square. |
| Side of a square X 1.12837 = the dia. of equal circle. |
| Square root of an area X 1.12837 = the dia. of equal circle. |
| Surface of cylinder = area of both ends + length X circum. |
| Surface of cone = area of base + 1/2 (slant height X circum. of base). |
| Surface of sphere = dia. squared X 3.14159. |
| Solidity of sphere = dia. cubed X .5236. |
| Solidity of cylinder = area of one end X length. |