Q 12-14-034NEETJEE MainMedium
The minimum number of two-input NAND gates needed to build an AND gate is
Answer: (D) $2$
One NAND gate gives $\overline{A\cdot B}$. A second NAND gate with its two inputs joined acts as a NOT gate and inverts this to $A\cdot B$. So two gates are enough, and one is not.
Solution by Sreeraj P, M.Sc Physics