Digital techniques__Logic Gates

• OR operation represents addition, AND operation represents multiplication. 
• NOR is opposite of OR operation. it is NOT OR that is complement of OR operation. 
• similarly NAND operation is opposite of AND operation. it is NOT AND that is complement of AND operation.
•  EXOR is exclusive OR. it produces low output for similar input and high output for dissimilar input. 
• likewise EXNOR is exclusive NOR gate produces high output for similar input and low output for dissimilar inputs.