Nand

NAND is one of the seven logic gates and it is similar to AND, but it has a ittle difference. The difference is a little circle in tail. The little circle means NAND works opposite AND in addition it has a difference in output.
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X=AB

A	B	X
0	0	1
0	1	1
1	0	1
1	1	0

this table shows when A and B 0 the X=1
When A and B 1/0 the X=1
But when A and B 1/1 the X=0