Why is the number "45" significant in the layout of the number cards and golden bead materials?

The number "45" is significant in the Montessori method as it is the sum of the first nine natural numbers. This concept is often introduced to students to help them understand basic principles of addition and the relationship between numbers. When children experience adding the numbers 1 through 9 (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9), they arrive at the total of 45. This foundational mathematical concept not only reinforces arithmetic skills but also allows children to engage with numbers through tangible materials, fostering a deeper understanding of numerical relationships and the concept of accumulating quantities.

The other options, while interesting in other mathematical contexts, do not relate directly to the Montessori materials in the same way. For example, the significance of prime numbers and other numerical sums, as well as educational benchmarks, may not directly tie into the hands-on learning approach that Montessori emphasizes with physical materials like the golden beads and number cards.