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Numbers trick

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lovejoy0120 | 00:06 Sat 14th Oct 2006 | How it Works
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When you multiply a 3 digit number by 7,by 11 and by 13 you get the number twice e.g. 489 x 7 x11 x13 = 489489.
When you multiply a 5 digit no. by 11 and by 9091 you get the same as above e.g. 54698 x 11 x9091 = 5469854698.

How does this work ?

Thanks
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Avatar Image naz_nomad
it's all to do with the magical number 9
00:20 Sat 14th Oct 2006
Avatar Image kempie
7 x 11 x 13 = 1,001

therefore the product of this and any 3-digit No. XYZ will be XYZXYZ.

11 x 9091 = 100,001

and gives the same result for 5-digit Nos.

01:12 Sat 14th Oct 2006
Avatar Image kempie
Here's one I cobbled together...

Take a 2-digit No. and multiply by 3, 7, 13 and 37.
01:17 Sat 14th Oct 2006
Avatar Image lovejoy0120
Question Author
And how did you make that one up ?
21:45 Sat 14th Oct 2006

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