The Bank Game is undoubtedly one of Montessori's absolute masterpieces. Through specifically created bead combinations and colour coded quantity cards - students as young as 4 and 5 can combine calculations to 9,999. A child can easily hold 1000 beads in cube format in the palm of a hand and compare that with jaw dropping interest to the golden unit bead held in the other. There are 10 bars and 100 squares and thousand cubes to manipulate, combine, match and calculate. This inquisitive young mind can began adding, historically thought "larger numbers", with ease. From here multiplication - an extension of addition is logically next introduced. Division is the "opposite" of multiplication...and so it goes.
Even with this outstanding piece of material able to reinforce so many concepts - Montessori created parallel exercises to fortify already simmering abstraction. The bead frames, strip boards, the finger charts and racks and tubes are but a few of the mathematical function material available for exploration. Repetition breeds retention!