In details

The magic number


1089 is known as the magic number. See why:

Choose any number from three distinct digits: for example, 875.
Now write this number backwards and subtract the smallest from the largest:
875 - 578 = 297

Now also invert this result and make the sum:
297 + 792 = 1089 (the magic number)

Warning: Before you send us an email saying that it doesn't work with certain numbers, please remember that three digits must be used in the calculation. Example:

574 - 475 = 099
099 + 990 = 1089