2.4.2 Subtraction
Subtracting two single-digit binary numbers is relatively simple:
(i) 0 - 0 = 0
(ii) 1 - 0 =0
(iii) 1 - 1 = 0
(iv) 0 - 1 = 1 ; Borrow = 1 or 10 - 1 = 1
Subtracting a positive number is equivalent to adding a negative number of equal
absolute value; computers typically use two’s complement notation to represent
negative values. This notation eliminates the need for a separate “subtract” operation.
The subtraction can be summarized with this formula: