How Does Mathematics Support Design?

i was thinking about this idea of a central question that i was kind of wrestling with it and struggling with it, and tried to think of applying to some things that are happening at my school at the moment. So again, without knowing all the details, i'm just going to think out loud some of thesemen ibes as shar but a, how does mathematics support design? Who is our audience and what do they need? What makes quality work? Or how do we know our design is working? Im those are a few examples of fairly generic, essential questions. But notice that they could be applied to primary kids building something through engineering. This hasn't been driven by an essential question.