Always End With 1089
Add two numbers together and always end with 1089.
Here is How:
Pick a three digit number. The three digits 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
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
891 + 198 = 1089
The answer will be 1089
So why does it do this?
Find out here
Footnotes
* But I ended with 198 not 1089 ... !
This happens if you pick a number like 546.
546 goes like this: 645−546=99, then 99+99=198.
BUT if you assume that 099 is a 3 digit number, you will get:
990−099=891, and 891+198=1089
* If you don't pick three different digits then this might happen:
343−343=0, 0+0=0