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- Question
- Which of the following numbers is prime?
Options- A. 119
- B. 187
- C. 247
- D. None of these
- Correct Answer
- None of these
Explanation119 is divisible by 7, 187 is divisible by 11,247 is divisible by 13 and 551 is divisible by 19. So none of the given numbers is prime.
- 1. The number (10 n-1) is divisible by 11 for?
Options- A. All Values of n
- B. Odd values of n
- C. Even values of n
- D. n = multiples of 11 Discuss
- 2. What least number must be added to 1056 get a number exactly divisible by 23?
Options- A. 21
- B. 25
- C. 3
- D. 2 Discuss
- 3. What least value must be given to * so that the number 97215*6 is divisible by 11?
Options- A. 1
- B. 2
- C. 3
- D. 5 Discuss
- 4. What least value must be given to * so that the number 6135 * 2 is exactly divisible by 9?
Options- A. 0
- B. 1
- C. 2
- D. 3 Discuss
- 5. What least value must be given to * so that the number 91876 * 2 is divisible by 8?
Options- A. 1
- B. 2
- C. 3
- D. 4 Discuss
- 6. If in a long division sum,the dividend is 380606 and the successive remainders from the first to the last are 434, 125 and 413, then the divisor is?
Options- A. 451
- B. 843
- C. 4215
- D. 3372 Discuss
- 7. A number consists of two digits. The sum of the digit is 10. On reversing the digits of the number, the number decreases by 36. What is the product of the two digits?
Options- A. 21
- B. 24
- C. 36
- D. 42 Discuss
- 8. The sum of 5 consecutive odd numbers is 190. What is the sum of the largest and the smallest numbers?
Options- A. 75
- B. 77
- C. 76
- D. 73 Discuss
- 9. If a =16 and b= 5, the value of (a 2+ b 2+ ab) / (a 3 - b 3) is?
Options- A. 1/11
- B. 1/19
- C. 121/3971
- D. None of these Discuss
- 10. Five time of a position integer is equal to 3 less then twice the square of that number. Find the number.
Options- A. 3
- B. 13
- C. 23
- D. 33 Discuss
Number System problems
Search Results
Correct Answer: Even values of n
Explanation:
For even values of n, the number (10n - 1 ) consists of even numbers of nines and hence it will be divisible by 11.
Correct Answer: 2
Explanation:
On dividing 1056 by 23, we get 21 as remainder
? Required number to be added = (23 - 21 ) = 2.
Correct Answer: 3
Explanation:
If sum of ODD positioned digits minus the sum of the EVEN positioned digits is divisible by 11 then the number is divisible by 11.
Sum of odd positioned digits - sum of even positioned digits = (9 + 2 + 5 + 6) - (7 + 1 + x) =14 - x
It must be divisible by 11. So x = 3.
Correct Answer: 1
Explanation:
6 + 1 + 3 + 5 + x + 2 = 17 + x must be divisible by 9.
So, x =1.
Correct Answer: 3
Explanation:
By hit and trial we find that 632 is divisible by 8. So, * must replaced by 3.
Correct Answer: 843
Explanation:
Let d = divisor and q = quotient
First remove the last remainder:
d x q + 413 = 380606
d x q = 380193
So d cannot be even (choice d) or a multiple of 5 (choice c).
If we try choice a or b,
a quick division (by calculator) shows that
380193 = 451 x 843, the other two choices.
(In the absence of choices, we could find the prime factors of 380193,
which are 3 x 11 x 41 x 281 and get various candidate divisors from that.)
So one of them is the divisor and the other the quotient.
So we can just check the first remainder:
843 x 4 = 3372
3806 - 3372 = 434 ... a match!
And just to be sure:
451 x 8 = 3608
3806 - 3608 = 198
So the divisor is 843.
Correct Answer: 21
Explanation:
Let the unit digits of the number be N and 10s digit be M
? Number = 10M + N
According to the question
MN = 10 .......(i)
And 10N + M = (10M + N) - 36
? 10N + M - 10M - N = -36
? 9N - 9M = - 36
? N - M = -4 .......(2)
On Adding eq. (i) and (ii) we get
N + M = 10
N - M = - 4
2N = 6
? N = 3 and M = 7
? Required product of two digits = 3 x 7 = 21
Correct Answer: 76
Explanation:
Let the five consecutive number are N - 2, N - 1, N, N +1, N+2
Sum of numbers = 190
? N-2 + N -1 + N + N + 2 = 190
? 5N = 190
? N = 38
Sum of largest and smallest numbers = (N + 2) + (N - 2)
= 2N = 2 x 38
= 76
Correct Answer: 1/11
Explanation:
Given Exp. = (a2+ b2+ ab) / (a3-b3)
= 1 / (a - b)
= 1 / (16 - 5)
= 1/11.
Correct Answer: 3
Explanation:
Let the number be N
According to the question 5N = 2N2 - 3
? 2N2 - 5N -3 = 0
? (N - 3) (2N + 1) = 0
N = 3 & -1/2
Thus the required number is 3
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