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The symbol and truth table of the NOT gate are given below:

Truth table of NOT gate
A A'
A A'
Symbol of NOT gate 0 1
1 0
3.7.2 AND Gate
The AND gate is a logical gate that always gives a single output for two or more input signals. The AND gate requires at
least two inputs and is called a binary gate. It produces a high output (1) only when all the inputs are high (1). In all
other cases, a low output (0) is produced. AND operation is represented by a dot (.).
The symbol and truth table of the AND gate are shown below:

A A . B A A . B . C
B
B C
Symbol of AND gate

Truth table of a two-variable AND gate Truth table of a three-variable AND gate
A B A.B A B C A.B.C
0 0 0 0 0 0 0
0 1 0 0 0 1 0
1 0 0 0 1 0 0
1 1 1 0 1 1 0
1 0 0 0
1 0 1 0
1 1 0 0
1 1 1 1
3.7.3 OR Gate
A logical gate that results in inclusive disjunction is called an OR gate. The OR gate is a binary gate. It produces high
output (1) when any one input is high (1). Only when all the inputs are low, 0 is produced as an output. The OR
operation is represented by a plus (+). The symbol and truth table of the OR gate are shown below:

A A+B A A+B+C
B
B C
Symbol of OR gate Symbol

Truth table of a two-variable OR gate Truth table of a three-variable OR gate

A B A+B A B C A+B+C
0 0 0 0 0 0 0
0 1 1 0 0 1 1
1 0 1 0 1 0 1
1 1 1 0 1 1 1
1 0 0 1
1 0 1 1
1 1 0 1
1 1 1 1

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