We are learning about it and my teacher didn't explain why either Sigma nor Pi were used.

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    $\begingroup$ I'm really not sure but to me Sum starts with and "S" and Product with a "P". See the connection ? $\endgroup$
    – Zubzub
    Nov 8, 2016 at 20:07
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    $\begingroup$ Possible duplicate of Why sigma notation? For product see here. $\endgroup$ Nov 8, 2016 at 20:14

2 Answers 2


It's phonetic - $\Sigma$ stands for "sum" and $\Pi$ stands for "product.


$\pi$ is a capital letter from the Greek alphabet called “Pi", it corresponds to “P” in our alphabet. So, "p"roduct notation is derived from the symbol of "Pi", $\pi$. A similar reasoning holds for the summation symbol, sigma.


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