1089

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Advice For New Users

Here's a neat trick:

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)

Now add these two numbers

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

Does it always work?
What about with 4 digits?

David Acheson has written a wonderful little book called "1089 and all that." Most highly recommended.

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