Question

the difference of a two digit number and the number obtained on reversing the digit is always divisible by 9 (true or false) ​

Answer 1

Yes!

Explanation:

I know this from having been a bank teller. But let's examine the math.

Any two digit number can be written as 10x + y.

Reverse the digits would give you

10y + x

Subtract to find the difference.

10x + y - (10y + x)

10x + y - 10y - x

10x - x - 10y + y

9x - 9y

9(x - y)

Yes, it has 9 as a factor, so it is a multiple of 9.