1. Good post? |

1) What is the value of x if x/2=n!
a)??
b)360
c)??
d)520
e)1440

2. Good post? |

E is the Ans ..

2*7!= 1440

Saurabh Malpani

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Can u explain how u got it

Thanks

4. Good post? |

E is the ans since 2*6! = 1440. But I just simply do the computation.

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how to do such a calculation in ONE MINUTE???
actually this is my only problem...i do not find the question difficul, but the timeeeeeeeeeeeeeeeeeeeeeeeeeee

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Yes, i also having the same problem as lorcar!

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1! = 1
2! = 2
3! = 6
4! = 24
5! = 120
6! = 720
7! = 5040
From answer choices, we can guest x=1440.

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one of my friend told that, since this is not a large number, we can remember it. And I have to admit that he has very good memory.

9. Good post? |
Anyone can explain this question?

10. Good post? |
Originally Posted by bscout
Anyone can explain this question?
Very simple, if we use reverse substitution.

Factorial of a number is 1*2*3*4*...*n.
Hence possible factorials are :
1! = 1
2! = 2
3! = 6
4! = 24
5! = 120
6! = 720
7! = 5040

Now x = 2*n! If we look for all the options, only 1440 makes sense.