Question

The difference between a 2-digit number and the number obtained by interchanging its digits is 63. What is the difference between the digits of the number?

Answer 1

Let units place digit = x

and tens place digit = y

Then number = x + 10y.

By interchanging the positions of the digits then

units digit = y

and tens digit = x

$\therefore$ Number = y + 10x.

$\therefore$ (x + 10y) – (y + 10x) = 63

$\Rightarrow$ x + l0y – y – 10x = 63

9y – 9x = 63 $\Rightarrow$ 9(y – x) = 63

$\therefore y-x=\frac{63}{9}=7$

Hence, difference of its digits = 7 Ans.