Aptitude - Problems on Numbers
- Problems on Numbers - 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.
What is the two-digit number? | |
I. | The difference between the two-digit number and the number formed by interchanging the digits is 27. |
II. | The difference between the two digits is 3. |
III. | The digit at unit's place is less than that at ten's place by 3. |
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).
What is the two-digit number? | |
I. | Sum of the digits is 7. |
II. | Difference between the number and the number obtained by interchanging the digits is 9. |
III. | Digit in the ten's place is bigger than the digit in the unit's place by 1. |
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).