Question

the sum of the digits of a 2 digit number is 7. the number obtained by reversing the digits, exeeds the original number by 9 . find the number

Answer 1

Assume the no. to be X.

X has got two digits A (Tens) and B(Ones)

ie., X = 10A + B

If the no. is reversed, the no. would be 10B + A

The difference between the two nos. is 9

Hence 10A + B -(10B + A) = 9

9A - 9B = 9

A - B = 1

As given in the problem, the sum of the two digits is 7.

A - B = 1

A + B = 7

Hence A = 3 and B = 4.  

The no. is 34