Fill in the blanks to make the statements true.

The difference of a two-digit number and the number obtained by reversing its digits is always divisible by ………………….. .

Let x and y be the digits in a two-digit number A = xy.

Reversing the digits, we get B = yx.

Sum of the digits in A is (10x + y).

Sum of the digits in B is (10y + x).

Difference S = A + B = (10x + y) - (10y + x).

S = 10x-x-10y + y = 9x-9y = 9(x-y)

The number is divisible by 9.