Abstract: A computer-implemented method of generating an item number for an item is disclosed. First, an item-type table is created and a sequence of specification codes on the item-type table is determined. After creating a code table for each of the specification codes, a specification name for each of the specification code is input into the code table. After inputting representative codes into the code table, an item-type code is input into the item-type table. After inputting a specification description into the item-type table, an item-number-encoding table is created and an item type of the item is selected on the item-number-encoding table. Next, an item-type code of the item is input into the item-number-encoding table, and then specification descriptions of the item type is shown on the item-number-encoding table. After deciding the representative codes according to real properties of the item, the item number of the item is generated.