Q:

(51 + 52 + 53 + .........+100) is equal to

Answer

51 + 52 + 53 + ...........+ 100


 = (1 + 2 + 3 + .... + 100) - (1 + 2 + 3 + ...... + 50)


 = It is in the form of n(n+1)2 series summation


= n1 = 100 , n2 = 50


=100100+12 - 5050+12


 =  (5050 - 1275) = 3775

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289 57483
Q:

Find the next number in the series 125, 80, 45, 20, ....

 

A) 5 B) 15
C) -5 D) 10
 
Answer & Explanation Answer: A) 5

Explanation:

The pattern is -45, -35, -25, -15

The next number = 20-15= 5

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39 53826
Q:

What least number must be subtracted from 13601, so that the remainder is divisible by 87 ?

A) 23 B) 31
C) 29 D) 37
 
Answer & Explanation Answer: C) 29

Explanation:

87)13601(156
       87
       -----
       490
       435
        -----
        551
        522
         -----
         29
         -----
Required number is 29.

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190 44954
Q:

If the product 4864*9 P 2 is divisible by 12, the value of p:

A) 1 B) 2
C) 3 D) 4
 
Answer & Explanation Answer: A) 1

Explanation:

Clearly 4864 is divisible by 4
So, 9 P 2 must be divisible by 3. So (9+P+2) must be divisible by 3.
So P=1.

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73 41308
Q:

The sum of all two digit numbers divisible by 5 is

A) 945 B) 678
C) 439 D) 568
 
Answer & Explanation Answer: A) 945

Explanation:

Required numbers are 10,15,20,25,...,95
This is an A.P. in which a=10,d=5 and l=95.
Let the number of terms in it be n.Then t=95
So a+(n-1)d=95.
10+(n-1)*5=95,then n=18.
Required sum=n/2(a+l)=18/2(10+95)=945.

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112 40418
Q:

A boy multiplied 987 by a certain number and obtained 559981 as his answer. If in the answer both 98 are wrong and the other digits are correct , then the correct answer would be :

A) 553681 B) 555181
C) 555681 D) 556581
 
Answer & Explanation Answer: C) 555681

Explanation:

987 = 3 * 7 * 47.
So, the required number must be divisible by each one of 3, 7, 47
553681 => (Sum of digits = 28, not divisible by 3)
555181 => (Sum of digits = 25, not divisible by 3)
555681 is divisible by each one of 3, 7, 47.

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58 34021
Q:

How many of the following numbers are divisible by 132?

264,396,462,792,968,2178,5184,6336

A) 4 B) 5
C) 6 D) 7
 
Answer & Explanation Answer: A) 4

Explanation:

132 = 4 x 3 x 11, So if the number is divisible by all three numbers 4,3 and 11,then the number is divisible by 132 also.
264   => 4,3,11(/)
396   => 4,3,11(/)
462   => 11,3
792   => 4,3,11(/)
968   => 11,4
2178 => 11,3
5184 => 3,4
6336 => 4,3,11(/)
Required number of numbers=4.

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31 34016
Q:

476 ** 0 is divisible by both 3 and 11.The non zero digits in the hundred's and ten's places are respectively:

A) 6 and 2 B) 8 and 2
C) 6 and 5 D) 8 and 5
 
Answer & Explanation Answer: D) 8 and 5

Explanation:

Let the number  be 476ab0 

 

476ab0 is divisible by 3 

=> 4 + 7 + 6 + a + b + 0 is divisible by 3

=> 17 + a + b is divisible by 3 ------------------------(i)

 

476ab0 is divisible by 11

[(4 + 6 + b) -(7 + a + 0)] is 0 or divisible by 11

=> [3 + (b - a)] is 0 or divisible by 11  --------------(ii)

 

Substitute the values of a and b with the values given in the choices and select the values which satisfies both Equation 1 and Equation 2.

 

if a=6 and b=2, 

17 + a + b = 17 + 6 + 2 = 25 which is not divisible by 3 --- Does not meet equation(i).Hence this is not the answer

 

if a=8 and b=2, 

17 + a + b = 17 + 8 + 2 = 27 which is divisible by 3 --- Meet equation(i)

[3 + (b - a)] = [3 + (2 - 8)] = -3 which is neither 0 nor divisible by 11---Does not meet equation(ii).Hence this is not the answer

 

if a=6 and b=5, 

17 + a + b = 17 + 6 + 5 = 28 which is not divisible by 3 --- Does not meet equation (i) .Hence this is not the answer

 

 

if a=8 and b=5, 

17 + a + b = 17 + 8 + 5 = 30 which is divisible by 3 --- Meet equation 1

[3 + (b - a)] = [3 + (5 - 8)] = 0 ---Meet equation 2

Since these values satisfies both equation 1 and equation 2, this is the answer

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33 33617