Tape measure repeat measurements

how do I make multiple equal marks with the tape measure tool?

I don’t know exactly what you are trying to do, but a guideline acts like any other object when you move it: you can tap [ctrl] and it will duplicate it, then you can use [/ nn] to get nn equal divisions of guidelines or [x nn] to get nn multiple guidelines.

You can also r-click on an edge and “divide” to get end points/nodes that the measure tool can snap to.