Addition of two binary numbers

5  -->   101
7  -->   111
---------------
12 ---> 1100

Note: In binary addition, 1 + 1 = 10. The rightmost digit (0) is written as the sum, and the leftmost digit (1) is carried over to the next column. Similarly, 1 + 1 + 1 = 11, so 1 is written as the sum, and 1 is carried over.