AND from NAND gates only — AND gate

Why this example is worth doing

Building AND from NANDs takes two gates: one NAND to compute the complement, one more with its inputs tied to invert it back. The page shows the algebra alongside — ((A·B)′)′ = A·B by involution — and makes the economic point that this is why real libraries do not bother: since NAND is the cheap primitive, a design that wants AND usually restructures to absorb the inversion elsewhere rather than paying for a second gate.

Try your own input in the AND gate. Truth table, symbol and algebraic form for A·B, with a live two-input toggle.