# Digital - Boolean Algebra - 2

+1 vote
How many NAND gates do you need to build a NOR gate?
(A) 2
(B) 3
(C) 4
(D) 5
reshown May 14

$\overline{A + B} = \overline{A} . \overline{B} = A'B' =((A'B')')'$

(A . A)' = A'

Now, we can get A' by using 1 NAND gate.

Similarly, we can get B' by using 1 NAND gate.

Now, we have to perform 1 NAND operation for which we need 1 NAND gate. We get (A'B')' as the output.

Now, we have to take complement of this output for which we need 1  NAND gate. Now, the output is ((A'B')')'.

((A'B')')' = (A+B)'

So, totally, we need 4 NAND gates in order to build a NOR gate.

Ans.: 4

answered May 14 by (6,690 points)
selected May 14 by

4 NAND gates are required. Check the below link for further information.

https://www.instructables.com/id/NOR-gate-from-NAND-gate/

answered May 14 by (1,880 points)

so 4 NAND gate required. C is the correct answer.

answered May 14 by (5,020 points)