The actual quantity of the dangerous goods must be shown on the DGD. Solids must be shown in kilograms and liquids and gases msut be shownj in litres. In some cases, you are obligated to show the gross weight of the package. At any rate, the true actual quantity must be shown on the DGD. Consequently, there is no rule for truncating.
When there are multiple packages with the quantity differing with each package, you need to declare the packages using multiple lines in full text. Abbreviated entry is not permitted.