Which term refers to the upper and lower limits of a series of numbers?

The term that refers to the upper and lower limits of a series of numbers is "Range." In mathematics and statistics, the range is calculated by subtracting the smallest number in a set from the largest number. This concept is important as it provides a measure of the spread of values in a dataset, helping to understand how much variation exists within that set of numbers.

Other terms like "Span," "Spread," and "Scope" could refer to concepts related to distance or coverage, but they do not specifically denote the limits of a numeric series. "Span" often relates to the entirety of something across a period or distance, "Spread" can indicate how widely something is distributed, and "Scope" generally refers to the extent of something. However, when discussing the specific upper and lower limits within a numerical context, "Range" is the correct choice.