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#1 2010-01-02 23:57:20
- Jai Ganesh
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- Registered: 2005-06-28
- Posts: 48,420
1 digit
Is ABCDABCD, where A,B,C,D is a 1 digit Whole number, is always a nonprime?
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#2 2010-01-03 00:48:38
- JaneFairfax
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- Registered: 2007-02-23
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Re: 1 digit
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#3 2010-01-03 18:52:38
- Jai Ganesh
- Administrator
- Registered: 2005-06-28
- Posts: 48,420
Re: 1 digit
Well Done!
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#4 2010-01-04 01:09:19
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: 1 digit
Hi ganesh;
The number ABCDABCD can bne represnted as:
Simplified to:
Each coefficient factors like this: Just counting unique factors:
10001000 = 2*5*73*137
1000100 = 2*5*73*137
100010 = 2*5*73*137
10001 =73 * 137
So, the number cannot be prime because it is clearly divisible by 37 and 173.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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