Answer:
See below
Explanation:
Because sometimes you have to 'carry' a 1 over to the ext column when adding two binary numbers
Example :
1 1 1
+1 1 1 <==== starting in the first R column add 1 + 1 to get 0 and carry 1
then the next column you will add 1 + 1 + 1 = 1 and carry 1 again
then 1 + 1 + 1= 1 and carry 1 again (to column 4) to get
1 1 1 0
