Which of the following is not a prefix in the metric system?

In the metric system, prefixes are used to denote various powers of ten, enhancing the system's simplicity and scalability. Each of the listed prefixes corresponds to a specific factor when multiplying or dividing the base units.

Giga corresponds to (10^9), indicating one billion times the base unit. Mega represents (10^6), which is one million times the base unit. Hecto is associated with (10^2), representing one hundred times the base unit.

Deca, however, corresponds to (10^1), which means ten times the base unit. Although it is indeed a recognized metric prefix, in certain contexts, it is considered less commonly used compared to the other prefixes listed. This is particularly true in areas such as scientific notation where larger prefixes like Giga and Mega dominate. Thus, its relative obscurity in practice might lead to confusion about its status as a "metric prefix."

In summary, while Deca is technically still part of the metric system and used in specific scenarios, it is less significant in broader scientific contexts when compared to prefixes like Giga, Mega, and Hecto. This distinction contributes to its selection as the answer to the question about which prefix is not commonly recognized or prioritized in the metric system