Category:Divisibility by 7

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This category contains pages concerning Divisibility by 7:


An integer $X$ with $n$ digits ($X_0$ in the ones place, $X_1$ in the tens place, and so on) is divisible by $7$ if and only if:

$\ds \sum_{i \mathop = 0}^{n - 1} \paren {3^i X_i}$ is divisible by $7$.

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Pages in category "Divisibility by 7"

The following 3 pages are in this category, out of 3 total.