This might be nitpicking, but your instructable title includes "without measuring", and your first instruction in the video is that you'll be needing a measuring device. I get that we're measuring something that's easier to divide, but we're still measuring, so your title is incorrect.

From your title, I'd have expected to be able to do this using pure geometry, instead of ever having to interact with arbitrary units of measure. This is not what you're showing, so it shouldn't be the implication of the title.