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Always End With 1089

Add two number together and always end with 1089.

Here is How:

Pick a three digit number. The three numbers used must be different. i.e. 123 Reverse that number. 123 becomes 321
Take the smallest three digit number from the largest.
321 - 123 = 198
Take the answer and reverse that number. 198 becomes 891
Add that number to the answer of the subtraction. 891 + 198 = 1089

The answer will be 1089!

So Why does it do this?
Find out here


A Little Footnote
But I ended with 198 not 1089. This happens if you pick a number like 546. Try to pick consecutive numbers like 123, 345, 765 etc. If it does happen, it is not a problem. Just repeat the stages again starting from 198.