friends..how could you make a full adder using two half adders....pls show me how would you do that with boolean expressions.......i.e...taking a full adder logical expression and then simplifying it to get two half adders......pls ..............urgent

hi murali

the logical expression of half adder is  A and B are inputs 

S = A XOR B             C =  A . B      S is SUM C is carry over BOTH ARE OUTPUT

the logical expression of full adder is

A , B,C are inputs

S = A XOR B XOR C         C = ( A XOR B ) . C +  A . B      ARE THE OUPUT  

so very clearly we can use half adder S output and another input C to get S = A XOR B XOR C 

and we have to use one OR gate also for C in full adder

so clearly we get XOR gate and AND gate from half adder which we can use to make FULL ADDER