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
number
s
Compare your answer with the title of this page...
Enrichment
:
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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