In ten fold dilution we add one part of the sample into the nine part of the diluent e.g. water. It will make it ten fold dilute. If we have series of tubes to dilute then… after making the ten fold dilution in first tube, take the dilute sample from the first tube in same quantity as we added sample in first tube and add it to 2nd one. then then take the same quantity from 2nd one and add to third one and so on......... from the last tube we take the adjusted quantity of dilute sample and discard it. This will make the series of ten fold dilution. If you add one part substance to 10 parts of water, you get an 11-fold dilution. (MORE)