Binary Addition and Subtraction

Binary addition or subtraction is carried out as a very basic practice of Half Adders and Full Adders. Further since we know that subtraction is nothing but a complemented addition, we can use the methods of addition for subtractions as well.

The following figure shows the interrelationships of addition and subtraction methods-

Here it must be kept in mind that the -ve numbers will always be in 2's complement form and to avoid the error caused by overflow during addition operations, registers should be taken of sufficiently larger sizes.

Addition of two positive numbers:

Addition of positive to negative:

Addition of negative to positive:

Addition of two negative numbers: