Question

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

Answer 1

Let the digit in units place be '$b$' and digit in tens place be '$a$'

Then the number will be $=10a+b$

Reversed number will be $10b+a$

$(10b+a)-(10a+b)=63$

$\Rightarrow 9b-9a=63$

$\Rightarrow b-a=7$

Therefore, the difference between two digits of that number is $7$.