You must start with a point of origin. Some would say you should want big numbers for the beginning coordinates. Maybe, eventually, that would be suitable, but not to start with. Too unbalanced. I, forever the romantic idealist, prefer something more like:

*Key in...0,0,0*.
Not that it really matters - most seem to begin as an off-center irregular polygon - a combination of erratically placed entities that we just so happen to have the math to connect the dots of. About as tricky and fundamental as uniting those entities is balancing proportions. Even once you've designated dimensions, you may find yourself with a coincidence gap, and no matter how many times you
*click "Accept"*

*click "Accept"*

*click "Accept"*

*click "Accept"*
logic does not allow for the operation. The thing that gets most people though, is the construction plane. Novice drafters are usually unaware that there is more than one, when in fact, there are several. You can spend all of class working avidly on a project, and five minutes before the bell rings, you locate the spinner tool and give the whole thing a once-over before calling the teacher over to judge your work. Dumbstruck at the sight of the mess you see, you realize that you've been working on the wrong construction plane the whole time, you didn't input or output what you thought you had, your time is up, you have nothing to show for it, and you've just flunked CAD. The final, dreadful, realization is that school's out.

*File... Close... No*.