We were very surprised that DS seemed not very good at math. Then i casually mentioned that you need to understand math to understsnd science and suddenly DS 6 was totally into it, and we got him books about math which put it into his preferred area of interest - like the murderous maths.
I was reading about this gifted school in CT which teaches trig by doing navigation since that's why it was invented. Maybe you need to get his interest by coming from another angle - after all worksheets and stuff are boring, so who wouldn't hate it even though he's good at it!
DeHe