Why is excess notation and twos notation is needed?

Excess notation and two's complement notation are essential for representing signed integers in binary systems. Excess notation allows for the representation of both positive and negative values by shifting the range of numbers, making comparison and arithmetic operations simpler. Two's complement, on the other hand, is widely used because it simplifies binary arithmetic, enabling straightforward addition and subtraction without the need for separate handling of signs. Both notations facilitate efficient computation and data representation in digital systems.