Factors of which number are used in the metric system?

The metric system is fundamentally based on the number 10, which is the foundation for its structure and operations. This is because the metric system employs a decimal-based framework, meaning units are scaled by factors of ten. For instance, prefixes such as "kilo-" (1,000), "centi-" (1/100), and "milli-" (1/1,000) signify specific powers of ten, allowing for straightforward conversions between units.

Understanding that the metric system is designed around a base of ten helps users easily measure, convert, and understand various quantities. Thus, any calculations or measurements involving the metric system will inherently relate to the factors of ten, making it essential for scientific, engineering, and everyday applications where precision and simplicity are crucial.

While 5, 2, and 12 are important in various mathematical or measurement contexts, they do not serve as the core building blocks of the metric system, making ten the only appropriate choice in relation to this question.