Exercise :: Problems on Numbers  Data Sufficiency 2
 Problems on Numbers  Important Formulas
 Problems on Numbers  General Questions
 Problems on Numbers  Data Sufficiency 1
 Problems on Numbers  Data Sufficiency 2
Each of the questions given below consists of a question followed by three statements. You have to study the question and the statements and decide which of the statement(s) is/are necessary to answer the question.
1. 


Answer: Option E Explanation: Let the tens and units digit be x and y respectively. I. (10x + y)  (10y + x) x  y = 3. II. x  y = 3. III. x  y = 3. Thus, even all the given three statements together do not give the answer. Correct answer is (E). 
2. 


Answer: Option E Explanation: Let the tens and units digit be x and y respectively. I. x + y = 7. II. (10x + y)  (10y + x) = 9 x  y = 1. III. x  y = 1. Thus, I and II as well as I and III give the answer. Correct answer is (E). 