Excess 3

Question

In Excess 3 addition, the groups that have produced a carry we have to add 0011 to them and subtract 0011 from the groups which have not produced a carry during the addition. Can someone explain the logic of performing this step for me?

Answer 1

suppose two binary nos. are A and B

convert them into excess 3

(A+3) and (B+3)

when you add both result is(A+B+6)=(C+6)

CASE1: carry is not generated:

In bcd addition ans is C

i.e. C+3 in excess 3

but you got the ans C+6 so subtract 3

CASE1: carry is generated:

in bcd addition.... if carry is generated,add 6

i.e. C+6

now to convert it into excess 3 add 3.

Comments

Thanks a lot :)