# Video: Evaluating the Output of Multiple NOT Gates

The diagram shows three NOT gates connected as a part of a logic circuit. If the input is 1, what is the output?

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### Video Transcript

The diagram shows three NOT gates connected as a part of a logic circuit. If the input is one, what is the output?

Okay, so first of all in the diagram, we can see one NOT gate, two NOT gate, three NOT gates. They’ve been connected one after another such that the output for the first NOT gate becomes the input for the second NOT gate. And the output for the second NOT gate becomes the input for the third NOT gate.

Now, we’ve been told that the input is set to one. So we need to find out what the value of the output is. To work this out, let’s recall what a NOT gate does. So a NOT gate, also known as an inverter, takes anything into the input and reverses it.

So if the input is one, the output becomes zero. And if the input is zero, then the output becomes one. So fairly simplistic but very useful. So with that in mind, let’s see what happens when the input to this whole setup is one.

So this input one goes into the first NOT gate and gets inverted to a zero. But then, the zero becomes the input for the second NOT gate. And it gets inverted back to a one. And then, this one becomes the input for the third NOT gate getting inverted back to a zero.

And at that point, we’ve arrived at the output. So the output is going to be zero. Hence, for this particular setup of three NOT gates connected in this way, if the input is one, then the output is zero.