# Backpropogation faster than forwardprop

Why does backpropogation take fewer steps than forwardpropogation?
I gave an answer in 1st comment; please correct me if I am wrong.

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The reason:
In backpropagation, we already have the value in each step that we need for the next calculation, but in the case of forwardprop, we have to go through a long calculation to get the value such value of J, a etc.

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Hello @farhana_hossain,

I searched â€śfewer stepsâ€ť in the transcript of the video and canâ€™t find anything. Can you walk through how you came up with the idea that backprop takes â€śfewer stepsâ€ť than forward prop?

Cheers,
Raymond

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N x P steps in forward prop
N + P steps in backward prop

Alright, @farhana_hossain. So, it is not that backprop is faster than forward prop.

Instead, it is that computing gradients with backprop ( N + P ) is faster than computing gradients without backprop ( N x P ). Please watch the video again for getting the idea that it is not a comparison between forward prop and backprop, but a comparison between computing gradients with and without backprop.

As for why backprop is faster, I suggest this post.

Cheers,
Raymond

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