Yet another fine number for engineers is 3. This number is intrinsic to many basic qualities of life as an engineer sees it.

3 is the number of points that define a plane, and, therefore, are the number of legs of a stable chair or stool.

3 is also the number of coordinate lines in, what else, 3-dimensional space. When engineers break down forces into components, there are 3 directions into which the forces are defined. They are called, in very technical terms, x-, y-, and z-coordinates. Creative? Maybe not. But powerful? Most definitely.

An engineer can explain so many thing by breaking down the vectors of force or velocity into its 3 coordinate directions. Why did his kid wreck the car? 3-dimensional coordinate analysis of the speed and direction of the car, and the 3-dimensional interaction of the forces between the car tires and the road, should adequately explain why the car left the road and hit the tree. Sure, the engineer Dad could simply say that his son or daughter was going too fast. But a far better explanation, and possibly a far better punishment, would be to have the 3 dimensional forces and velocities sketched out in a very detailed explanation of the movement of the vehicle. A finite element analysis could be added, too, just for the fun of it.

3 can be a very powerful number.