Add two number together and always end with 1089.

Posted by teacher on March 1, 2007

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!
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.

Full Article