1(1!)+2(2!)+------+2012(2012!)=?

• 1(1!) can be written as (2-1)*1!= 2!-1!
  similarly 2(2)! can be written as (3-1)(2!)=3!-2!
  so the equation will become as 2!-1!+3!-2!+4!-3!........2013!-2012!
  out of which all will be cancelled out and only -1! and 2013! will be left so the answer is 2013!-1
• 10 years agoHelpfull: Yes(49) No(2)
• ans. 2013! -1
• 10 years agoHelpfull: Yes(2) No(8)
• 2013!-1
  use hit and try for 1st few terms, you will understand the pattern
  its sum(n*n!) from 1 to n = (n+1)!-1
• 10 years agoHelpfull: Yes(0) No(3)
• 2013!-1..as 1(1!)=2!-1!
  2(2!)=3!-2!
  3(3!)=4!-3! and so on..
  so the series becomes=2!-1!+3!-2!+4!-3!+....+2013!-2012!=2013!-1!=2013!-1(ans)
• 10 years agoHelpfull: Yes(0) No(1)