The document discusses different number systems including decimal, binary, octal, hexadecimal, BCD, gray code, and excess-3 code.
- Decimal uses base 10 with symbols 0-9. Binary uses base 2 with symbols 0-1. Octal uses base 8 with symbols 0-7. Hexadecimal uses base 16 with symbols 0-9 and A-F.
- BCD assigns a 4-bit binary code to each decimal digit 0-9. Gray code is a non-weighted cyclic code where successive codes differ in one bit. Excess-3 code derives from 8421 code by adding 0011.