Gre sub math score is low...Should I send to schools that strongly recommend ?

I got pretty bad Gre sub score,which is 51%. I am applying a couple of graduate programs in math, but most of them are masters. So should I send my Gre sub score to those who strongly recommend it ?(but not required) My other information:I come from a pretty good public schools, but not famous for math, GPA is 3.67, two REUs, and I guess my three letters are good.

Thanks !