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Manager
Joined: 29 Apr 2003
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The "reflection" of a positive integer is obtained by [#permalink]
 12 Dec 2003, 02:41
The "reflection" of a positive integer is obtained by reversing
its digits. For example, 321 is the reflection of 123.
The difference between a five-digit integer and its reflection
must be divisible by which of the following?
a. 2
b. 4
c. 5
d. 6
e. 9
I have chosen 2, e.g. 98721-12879 = 84942/2 = 42471.
But the answer is not. Can anyone try and explain the correct answer?
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Director
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five digit integer 98721 the reflection is 12789, not 12879 or 85932 is the difference , as in this case it is divisible by 2,4,6,9 not divisible by 5, we can not say. Try 10000-00001=9999, think it is clear now..
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Manager
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Sorry my mistake in reversing the order.
May I know it is a rule that when reversing any digits number, it would always be divisble by 9?
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Manager
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Difference between an integer and it's reflection is always divisible by 9. Of course by that logic it would also be divisible by 3. But that's just a site note.
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