and b0 to b3. and s0 to s3 are output and c1,c2,c3,c4 are the carry bits.
this figure shows an example of adding of two numbers 12 and 9 the decimal addtion of it is 21
.binary form of 12 is 1100 and 9 is 1001 so sum=0101 and the carry 1.
so our final output will be 10101.
the half adder produce the a sum of 1 and carry of 0, the first full adder produce a
sum of 0 and carry of 0 the second full adder produce a sum of 1 and carry of 0 and the third full adder produces a sum of 0 and carry is 1.so our final output is 10101.
using more full adders we can build more binary adders of any length.
