RRB Technician 2013 Ques 103
Question: The difference between a two-digit number and the number obtained by interchanging the two digits of the number is 9. The sum of the two digits of the number is 15. What is the product of the two digits of the two digit number?
Options:
A) 54
B) 72
C) 56
D) Cannot be determined
Show Answer
Answer:
Correct Answer: C
Solution:
- Let the digit of unit place be x. So, the digit of tens place will be $ (15-x) $ . Now, $ [10(15-x)+x]-[10x+(15-x)]=9 $
$ \Rightarrow $ $ 150-10x+x-10x-15+x=9 $
$ \Rightarrow $ $ 135-18x=9 $
$ \Rightarrow $ $ 18x=126 $
$ \Rightarrow $ $ x=7 $ Thus, the digits of the number are 7 and 8, So, the product of digits = 56
BETA
