A) Logic Gates (AND, OR, NOT, NAND, NOR, EX-OR): Review of all logic gates; AND, OR, NOT, NAND, NOR, EX-OR & their truth tables. Appropriate combinations of gates results into an amazing & innovative logical configuration. B) Number Systems (Binary, Octal, Decimal & Hexadecimal): In digital, we normally deal with four number systems of arithmetic (I) Binary (II) Octal (III) Decimal (IV) Hexadecimal. The commonly used number system by all of us is decimal, while the binary number system is used by computers.