Number Series - Aptitude Questions and Answers
Best Number Series Questions and Answers
Dear Readers, Welcome to Number Series Objective Questions have been designed specially to get you acquainted with the nature of questions you may encounter during your Job interview for the subject of Number Series MCQs. These objective type Number Series questions are very important for campus placement test and job interviews. As per my experience good interviewers hardly plan to ask any particular question during your Job interview and these model questions are asked in the Banks, SSC, Railways, Postal and many Govt Jobs.
1. 325325 is a six-digit number. It is divisible by:
A.7 only
B.11 only
C.13 only
D.All 7, 11 and 13
Ans: D
Explanation:
Clearly, 325325 is divisible by all 7, 11 and 13
2. The difference between the squares of two consecutive odd integers is always divisible by:
A.3
B.6
C.7
D.8
Ans: D
Explanation:
Let the two consecutive odd integers be (2x + 1) and (2x + 3)
Then, (2x + 3)2 - (2x + 1)2 = (2x + 3 + 2x + 1) (2x + 3 - 2x - 1) = (4 x + 4) x 2
= 8 (x + 1), which is always divisible by 8
3. In tow-digit number, the digit in the unit’s place is four times the digit in ten»s place and sum of the digits is equal to 10. What is the number?
A. 14
B. 18
C. 20
D. 28
Ans: D
Explanation:
Let the ten’s digits be x. Then, unit’s digit = 4x.
x + 4x = 10
5x = 10
x = 2.
So, ten’s digit = 2, unit’s digit = 8.
Hence, the required number is 28.
4. Three times the first of three consecutive odd integers is 3 more than twice the third. The third integer is:
A. 9
B. 11
C. 13
D. 15
Ans: D
Explanation:
Let the three integers be x, x + 2 and x + 4.
Then, 3x = 2(x + 4) + 3
x = 11.
Third integer = x + 4 = 15.
5. The difference between a two-digit number and the number obtained by interchanging the positions of its digits is 36. What is the difference between the two digits of that number?
A. 3
B. 4
C. 9
D. Cannot be determined
E. None of these
Ans: B
Explanation:
Let the ten's digit be x and unit's digit be y.
Then, (10x + y) - (10y + x) = 36
9(x - y) = 36
x - y = 4.
6. The sum of the digits of a two-digit number is 15 and the difference between the digits is 3. What is the two-digit number?
A. 69
B. 78
C. 96
D. Cannot be determined
E. None of these
Ans: D
Explanation:
Let the ten's digit be x and unit's digit be y.
Then, x + y = 15 and x - y = 3 or y - x = 3.
Solving x + y = 15 and x - y = 3, we get: x = 9, y = 6.
Solving x + y = 15 and y - x = 3, we get: x = 6, y = 9.
So, the number is either 96 or 69.
Hence, the number cannot be determined.
7. A number consists of two digits. If the digits interchange places and the new number is added to the original number, then the resulting number will be divisible by:
A. 3
B. 5
C. 9
D. 11
Ans: D
Explanation:
Let the ten's digit be x and unit's digit be y.
Then, number = 10x + y.
Number obtained by interchanging the digits = 10y + x.
(10x + y) + (10y + x) = 11(x + y), which is divisible by 11.
8. In a two-digit, if it is known that its unit's digit exceeds its ten's digit by 2 and that the product of the given number and the sum of its digits is equal to 144, then the number is:
A. 24
B. 26
C. 42
D. 46
Ans: A
Explanation:
Let the ten's digit be x.
Then, unit's digit = x + 2.
Number = 10x + (x + 2) = 11x + 2.
Sum of digits = x + (x + 2) = 2x + 2.
(11x + 2)(2x + 2) = 144
22x2 + 26x - 140 = 0
11x2 + 13x - 70 = 0
(x - 2)(11x + 35) = 0
x = 2.
Hence, required number = 11x + 2 = 24.
9. Find a positive number which when increased by 17 is equal to 60 times the reciprocal of the number.
A. 3
B. 10
C. 17
D. 20
Ans: A
Explanation:
Let the number be x.
Then, x + 17 = 60/6
x2 + 17x - 60 = 0
(x + 20)(x - 3) = 0
x = 3.
10. A number consists of 3 digits whose sum is 10. The middle digit is equal to the sum of the other two and the number will be increased by 99 if its digits are reversed. The number is:
A. 145
B. 253
C. 370
D. 352
Ans:B
Explanation: