The metal kings illustrate the decimal system. The colors of the kings correspond to the colors of the number cards for units, tens, and hundreds. The colors of place value appear repeatedly in many Montessori materials - chessboard, abacus, game of marks, etc. This is very memorable. The magnitude of the numbers is represented by the size of the kings, the green thousand is larger than the green unit.

The decimal kings are closely related to the story by Axel Winkler 'Of the Kings of the Decimal System' (BM 038), but can also provide additional help to the children when introducing the golden bead material and the number card set.