_The Number Nine._--Can any of your mathematical correspondents inform me
of the law and reason of the following singular property of the numbers?
If from any number above nine the same number be subtracted written
backwards, the addition of the figures of the remainder will always be a
multiple of nine; for instance--
972619
916279
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56340 the sum of which is 18, or 9 × 2.
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925012
210529
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714483 the sum of which is 27, or 9 × 3.
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83
38
--
45 the sum of which is 9.
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