Counting the number of organisms in a small area and multiplying to estimate thenumberin a larger area is called a

Sampling

Explanation:

Sampling is a statistical procedure in which a selected number of observations is used to represent the whole observation. When we take an area and we use the population to estimate that of other areas or the whole population, we are simply sampling. Sampling is very important to some specific forms of observations. Sampling can be done randomly or in a systematic way. The goal of sampling is using the part to represent the whole.