De Morgan’s Theorem

De Morgan’s Theorem are stated in two statement:
First Theorem

       “The complement of a sum equals the product of the complements”
(A+B)’ = A’.B’
NOR gate is logically equivalent to a bubbled AND gate

Second Theorem

“The complement of a product equals the sum of the complements”
(A.B)’ = A’+B’
NAND  gate is logically equivalent to a bubbled OR gate