Answer always comes 99

1)      1)Take any two digits number in which digits on tens place is greater than digits on ones place.

2)      2)Write the number in reverse order.

3)      3)Subtract the number of step II from the number of Step I.

4)      4)Add the reverse number of step III to the number of step III itself. Then, answer always comes 99.

e.g.  1) Any number is        92

2) The reverse of 92 is      -29

3) Difference                  63

4) Reverse of 63 is         +36

5) Ans:                      99

Reason:

1)      Difference between a two digits number & its reverse is always multiple of 9.

2)      Sum of result of (1) in two digits number & its reverse is always 11 times 9, i.e. 99.

Note that if a two digits number is x times 9, then its reverse must be (11-x) times 9.