The term 'field of operations' is a job description that refers to the area of expertise in which an individual works. In this case, the crossword solution for the term is 'ARITHMETIC, ' which is the branch of mathematics that deals with the manipulation of numbers and the study of the properties of numbers. ARITHMETIC is used in many different fields, such as accounting, engineering, and computer science. It is also used in everyday life, such as when calculating taxes or making purchases.