Question

The sum of digit of two digit number is 12 the number obtained by interchange into two digits exceeds the given number by 18 Find the number

Answer 1

Let the tens place digit be a

and unit place digit be b

According to first condition,

a + b = 12

=> a = 12 -b ----------(1)

According to second condition,

(10b + a) - (10a + b) = 18

=> 9b - 9a = 18

=> b - a = 2

=> b - ( 12 - b ) = 2

=> 2b - 12 = 2

=> 2b = 14

=> b = 7

Now,

a = 12 - b

=> a = 12 - 7

=> a = 5

Number = 10 (5) + 7

= 57