Abstract: Guide providing methods and an operator device are provided, one of methods comprises, acquiring item dimensions information and item constraint information of items and pallet dimensions information and pallet constraint information of pallets, classifying items into a plurality of item groups based on the acquired information, matching each of the item groups with a pallet for loading items included in a corresponding item group, when all items included in multiple item groups can be loaded together on a single pallet, merging the multiple item groups based on a remaining area of the matched pallet, performing a simulated loading of items included in each of the item groups on the pallet matched to a corresponding item group by changing loading sequences and arrangements, and determining a loading sequence and arrangement for loading the items included in each of the item groups on the pallet matched to the corresponding item group.