## Most recent change of 1089

Edit made on March 25, 2009 by GuestEditor at 22:38:37

Deleted text in red /
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WW

HEADERS_END

Here's a neat trick:

[[[>40 For example:

* Start with 672

* Reversing it gives 276

* 672 - 276 is 396

* 396 reversed is 693

* 396 + 693 is ... ?

]]]

* Pick any 3 digit number, where the first and last digits are different.

* Reverse it

* Subtract the smaller from the larger

* Take this answer and reverse it (insert a zero in the front first if it is not 3 digits still)

* Take this answer and reverse it

** (insert a zero in the front first if it is not 3 digits still)

* Now add these two numbers

Compare your answer with the title of this page...

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Enrichment:

* Does it always work?

* What about with 4 digits?

David Acheson has written a wonderful little book called !/ 1089 and all that. !/

David Acheson has written a wonderful little book called !/ "1089 and all that." !/

Most highly recommended.