Finding Factorials with Gamma
Community wiki for built-in solutions

This answer is intended to collect answers that are simply built-ins. It's a community wiki, so anybody can edit in without approval. Go ahead and include any built-in only solution here, following xnor's proposal and according to our consensus.

Jelly, 1 byte

!


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J , 1 byte

!


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2sable, 1 byte

!


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Pyth, 2 bytes

.!


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R, 9 bytes

factorial


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Stax, 2 bytes

|F


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Wolfram Language (Mathematica), 3 bytes

#!&amp;


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