math_applicant wrote:No, I meant high MGRE + good grades but from an unknown school. I was thinking MGRE can add credibility to the grades may be.
Yeah it doesn't really add much credibility. Because MGRE isn't a mathematics test. It tests how good you are at taking tests, gaming the system etc. And the admission committee knows this. Furthermore, it tests high school and introductory undergrad mathematics. Not research level stuff.
Also, applicants from top universities routinely score high on the MGRE. Compared to them, you will have the same high MGRE score but is disadvantaged in department reputation and sadly, the reputation of your recommenders (famous profs tend to be at famous universities).
While having a high MGRE does little, having a low MGRE does a lot to discredit your undergrad results. So I guess you could say "it helps" in that having a high MGRE saves you from the disadvantages of a low MGRE.