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發表於 2013-8-8 06:50:55
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In fact, you don't need just 2 digits number, 3 digit, 4 digits, 5 digits numbers, if you do the same - add up all the digit and subtract from the original, it would be the same- the result would be a multiple of 9.
As for why it is always a multiple of 9, I need to think a bit harder. I think that how "checksum" digit works. |
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樓主: 門小龍
在線雷達
發表於 2013-8-8 04:52:21
