An integer constant is any number in the range -32768 to +32767, because an integer constant always occupies two bytes in memory and in two bytes we cannot store a number bigger than +32767 or smaller than -32768. Out of the two bytes to store an integer, the highest bit is used to store the sign of the integer. This bit is 1 if the number is negative and 0 if number is positive. Unsigned integer constant is an integer constant which has the permissible range from 0 to 65536. Thus significance of declaring a constant as unsigned almost doubles the size of the largest possible value. This happens because on declaring a constant as unsigned, the sixteenth bit is free and is not used to store the sign of the constant.
