Does anyone know any good websites for figuting out serial dilutions?

what do you need a website for?
you take e.g. one ml of a liquid add 9 of water (or whatever your solvent is) to it and get a dilution 1:10
you take your 1:10 dilution, repeat the process. Now you have 1:100 and so on.
what is difficult about it???
All you have to know that 1:10 means one part OUT of ten if the substance of interest. So you add 9parts not ten of your solvent. Ditto for all other concentrations.

You add 1mL of your stock sltn to a test tube (#1) containing 9 mL of your dilution factor (usually a growth medium). For this test tube you now have a 10% conc. of your stock.

From the 10% conc. test tube (1) you take 1 mL of that solution and add it to another test tube (#2) containing 9 mL of dilution factor. Now for the second test tube you have a 1% conc. of you stock.

Stock: 100%
tube 1: 10% dilution=10^-1
tube 2: 1% dilution=10^-2
tube 3: 0.1% diluiton=10^-3

The idea in serial dilutions is to have a controlled amount of stock in a set ratio, used to easily calclate CFU's, or colony forming units on a plate. Is this what you need it for? If you need any more help just post!