I have been trying to create a ramp for cars, leading from the ground floor to the parking level and I have come across yet another cool feature.

This is what I was going for:

So I drew a floor and made one of the short edges define a slope:

Easy.

Now, since I knew the length of the ramp and the height I would normally dredge up my high-school math and find that in a triangle with a right angle I get the angle I need by taking the invertet tangent from the result of dividing the height by the length.

Or, and that's the nice part, I can simply divide the height by the length and type in the percentage I get!
And Revit will calculate the graded angle for me. Nice!