How do you make a 8 fold dilution?

An 8-fold dilution means you are making your solution 1/8 less concentrated. So, if you want to make 100 ml of a solution diluted 8 fold you would do as follows:

1/8=.125 100*.125= 12.5

Mix 12.5 mL of your concentrated solution with 87.5 mL of your solvent (water etc..) to bring the final volume to 100 mL.

If you wanted to perform a ten fold dilution you would simply mix 10 mL of your concentrated solution with 90 mL of your solvent.

1/10=.1 100*.1=10