sajjad

Hi I am going to apply for Phd programs in finance in US and Canada, I have a Bsc and Msc in Electrical Engineering and one minor major in Math, I have taken the GMAT but got a not very good score,,690 but I scored 100% in quantitative part,,,,, lately a friend of mine suggested it is a good idea to take a GRE subject in math,,, along with my GMAT scores. I do not know whether it would help or not? I can get a good score on GRE sub,,,but no business school requires this test,,,,,can somebody help me?