The first shall be the last, the last shall be...

[varoom]

Nope - not a religious post - I'll leave that to the 'experts' ;).

Pick a 3 digit # (digits must be different ie. 123 or 456)

Reverse that # (123 become 321)

Substract the smaller # from the larger (321 - 123 = 198)

Take the answer and reverse the # 198 becomes 891

Add that # to the substraction result:

891 + 198 = 1089

For a 3 digit # the answer will always be 1089. :D

[meese]

Another simple math trick based on the Decimal base 10 system (using the numbers 0-9). It also work in any other base.

Hexadecimal base 16 (0-F) will always give 10EF.

Octal base 8 (0-7) will always give 1067.

Binary base 2 (0-1) will always give 1001.

Note that the rightmost digit is always the highest number in the base (9 or F or 7 or 1), and the number second from the right is always 1 below that.

Unless, of course, the number you pick is symmetric, such as 313 or 676 or 555, then you just get 0 every time.

But hey, if it helps to pick winning lottery numbers, then who's to complain?