redfreakyppl

So I'm doing this science fair project & its due SOON. Its about the genotype (the gene make-up basically) of red hair. I'm trying to come up with all the possible combinations of the genes, but I can't figure out the right equation/formula. Here's the deal: There are 8 alleles for hair color. HHHHHHHH or hhhhhhhh or Hhhhhhhh or hHhhhhhhh or HHHHHHhH, etc. How do I find the # of combinations???