Question

If the number obtained by interchanging the digits of a two digit number is 18 more than the original number and the sum of the digits is 8, then find the original number.

• A. 25
• B. 35
• C. 40
• D. 30

Answer 1

The correct option is B 35

Let the given number be xy
xy can be written as 10x + y
According to the given data
xy = yx + 18
⇒ 10x + y = 10y + x + 18
⇒ 9y − 9x = 18
⇒y − x = 2 ………..(1)
and also its given that sum of digits = 8
⇒ x + y = 8 ………(2)
Solving equation (1) & (2) we get
2x = 6

x = 3 and y = 5
Hence the given number is 35.