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Number Theory?

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2 Answers

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  • 4 years ago

    When a number is congruent to 0 (mod "n"), it simply means that the number is exactly divisible by that number "n".

    In your question, the final total (including the check digit) must be congruent to 0 (mod 10), which means:

    -- the total is divisible by 10, which means the same as:

    -- the number ends with a zero.

  • 4 years ago

    The check digit should be 2

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