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Numerical Ability
Arithmetic
Find the sum of the series (1*1!+2*2!+3*3!+...........+2012*2012!)
Read Solution (Total 8)
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- General term is n*n!=((n+1)-1)*(n!)
=(n+1)*n!-1*n!
=(n+1)!-n!
S=(2!-1!)+(3!-2!)+(4!-3!)+.........+(2013!-2012!)
S=2013!-1!
=2013!-1 - 10 years agoHelpfull: Yes(29) No(2)
- 1*1!=1=2!-1
1*1!+2*2!=5=3!-1
1*1!+2*2!+3*3!=23=4!-1
and so on....
1*1!+2*2!+3*3!+...........+2012*2012!=2013!-1
- 10 years agoHelpfull: Yes(17) No(0)
- n*n!
= ((n+1)-1)*n!
=(n+1)*n!- n!
=(n+1)!-n!
putting values of n=1,2,......,2012
(2!-1!)+(3!-2!)+(4!-3!)+.........+(2013!-2012!)
=2013!-1 - 10 years agoHelpfull: Yes(4) No(0)
- (1*1!+2*2!+3*3!+...........+2012*2012!)
it can be written as
(2-1)1!+(3-1)2!+(4-1)3!+.........(2013-1)2012!
2!-1!+3!-2!+4!-3!+............2013!-2012!
2013!-1 ans - 10 years agoHelpfull: Yes(1) No(0)
- 2013!-1 as it satisfies the pattern
- 10 years agoHelpfull: Yes(0) No(0)
- add n and subtract n in each term where n=1,2,3,....2012. we get 2013!-1!.
- 10 years agoHelpfull: Yes(0) No(0)
- sum of series =2013!-1 [n*n!=(n+1)!-n!]
- 10 years agoHelpfull: Yes(0) No(0)
- 2013!-1;
E(n.n!)=E(n+1-1)n!=E(n+1)!-E(n!);
implies, ans is 2013!-1; - 10 years agoHelpfull: Yes(0) No(0)
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