E? wat is OA?
I use POE here. The difference in the last digit of the 5-digit number and its reflection can be odd or even, depending upon the last two digits are odd or even.
We are asked to find an answer that is always (must) true...so
2,4,6 all gone ( as they are multiples of 2 )
5 has a restriction that the difference should end in 0 or 5 which is not always true, so 5 is gone..
9 remains, I tried with 3-4 combinations and always got the diff as multiple of 9
May be someone else can have a better way..
The "reflection" of a positive integer is obtained by reversing its digits. For example, 321 is the reflection of 123. The difference between a five-digit integer and its reflection must be divisible by which of the following?
I would appreciate if you provide explanation along with an answer