What does a "calculator error number" typically signify?

A "calculator error number" or message typically signifies that the calculator cannot process the input or perform the requested operation for various reasons. This could be due to an invalid mathematical operation (like division by zero), exceeding the calculator's numerical limits (overflow), incorrect syntax in an expression, or attempting an operation outside the calculator's domain (e.g., square root of a negative number). It essentially alerts the user that the result cannot be computed or displayed correctly.