CAT 2006 | Question: 70

Question

When you reverse the digits of the number $13,$ the number increases by $18.$ How many other two digit numbers increase by $18$ when their digits are reversed?

• A. $5$
• B. $6$
• C. $7$
• D. $8$
• E. $10$

Answer 1

Let 10x + y be a two digit number. 

Its reverse = 10y + x

Now, 10y + x – 10x – y = 18

9(y – x) = 18

 y – x = 2

Thus y and x can be (1, 3), (2, 4), (3, 5), (4, 6), (5, 7), (6, 8) and (7, 9)  Other than 13,

 

Hence, option (2)6 is the Answer.