Latest Elitmus Aptitude Question SOLUTION: 4 childrens born in consective years,every year her mother calcilates the product of their ages,what is always true for that product: a) prime no. + 1 b)square of a number -1 c) a

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4 childrens born in consective years,every year her mother calcilates the product of their ages,what is always true for that product:
a) prime no. + 1
b)square of a number -1
c) always divied by 10

Asked In Elitmus Krishna kant dixit (10 years ago)

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RAKESH  (10 years ago)

i think ans should be (b)square of a number -1
check
1*2*3*4=5^2=1
2*3*4*5=11^2-1
3*4*5*6=19^2-1

Is this solution Helpfull? Yes (27) | No (2)  

Abhishek  (10 years ago)

answer should be a , prime no +1 i guess.

Is this solution Helpfull? Yes (7) | No (11)  

Sasanka Banerjee  (10 years ago)

ans is option b)square of a number -1 as rakesh had said earlier

@vikash 119 is divisible by 7 or 17 i.e. 7*17=119

& 3*4*5*6=360=361-1=19^2 -1

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sudheer  (10 years ago)

Ans:B
1*2*3*4=5^2-1
2*3*4*5=11^2-1
3*4*5*6=19^2-1
4*5*6*7=29^2-1
....soon..
product of the four consecutive numbers=((first*last)+1)^2-1
ie:n*(n+1)*(n+2)*(n+3)=((n*(n+1))+1)^2-1

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VIKASH KUMAR SINGH  (10 years ago)

a) prime no. +1
case I -> 1*2*3*4=23+1=24
case II -> 2*3*4*5=119+1=120
case III-> 3*4*5*6=359+1=360
case IV -> 4*5*6*7=719+1=720
5*6*7*8=1679+1=1680
.
.
.
.
here 23, 119,359,719,1679 all are prime no.
option B will be wrong because case III doesn't follow it and for option C case I doesn't follow it....

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anuj rajput  (10 years ago)

119 is not prime

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Harshil Bhatnagar  (10 years ago)

every prime number is 6n+-1.
n(n+1)(n+2) is always divisible by 6.
thus +1 would be a prime number

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