Diagram (A) shows the age-old technique to divide a line into any number of segments. You need a ruler (or tape measure) a good bit longer than the line to divide, to give you multiple options. I use a table edge to run the T-square along, but while you can use a clear drafting square… accuracy is more difficult. Why not use calculator? Well the second method does just that, but using a ruler and square is fast, and can be less tedious for craftspersons.
But! Here’s why you might be a little nerdy, or un-american for this technique to work.
To actually mark your points on the line, you need any one of the following:
In Adobe Illustrator or some superior CAD Program:
CAD: Select your given line and click Divide by Number of Segments, Enter #, Hit return. Pat yourself on back for knowing CAD.
Adobe Illustrator: Oh boy, here we go: