Another way:
1, scale the line by a factor of 1/n: Modify -> Scale, around one end (say, the start point), uniform scaling, and by a factor 1/n (yes, you can type in 1/3 instead of 0.333333, etc.);
2, copy, reference point=start point, target point = endpoint, number of copies = n - 1
ravas wrote
The "Snap Middle" mode allows you to choose different divisions.
That in combination with Modify->Divide could work.
Unfortunately the divide tool cancels itself after you divide something.