Final answer:
An operator is a sign or symbol in mathematics that instructs which calculation to be performed. For example, the Greek letter delta (Δ) signifies a change in a quantity, and a coefficient in chemistry represents the number of molecules in a balanced equation.
Step-by-step explanation:
A sign or symbol that indicates what calculation is to be performed is commonly known as an operator. In mathematics, these include symbols like + (plus), − (minus), × (multiplication), and ÷ (division), among others. Each of these operators instructs us to carry out a specific mathematical action with the numbers or variables they connect.
For example, the symbol Δ, which is the uppercase Greek letter delta, is used to indicate a change in a certain quantity. If we see Δx, it is understood as 'change in x'. Similarly, the symbol a with a bar over it (ā) denotes the average value of 'a'.
In chemistry, the term coefficient refers to a number that precedes a chemical formula in a balanced chemical equation, indicating the stoichiometric number of molecules or atoms involved in the reaction. In the context of numbers, the sign of a number, such as + or −, indicates whether the number is positive or negative relative to zero.