When scaling an object, you have two options for choosing the scale factor: You can enter an absolute number (such as 2, or 1/3), or you can scale by reference. Scaling by reference allows you to scale objects to a desired size without having to calculate the scale factor. To do this, type "R" at the command line after you pick a base point. Next, specify your current measurement, then enter the new distance. For example, if one side of an object is 5'-6" long and you want to expand it to 7'-3", use 5'-6" as the reference length and enter 7'-3" for the new length.