1*1!+2*2!+3*3!+4*4!+…….+2012*2012!

• 1*1!=1 => (2!-1)
  
  1*1!+2*2!= 1+4 = 5 => (3!-1)
  
  1*1!+2*2!+3*3! = 1+4+18 = 23 => (4!-1)
  
  1*1!+2*2!+3*3!+4*4!=1+4+18+96 = 119 => (5!-1)
  
  in the same way
  
  1*1!+2*2!+3*3!+4*4!+...+2012*2012! = (2013! - 1)
  
• 10 years agoHelpfull: Yes(32) No(0)
• 1*1!+2*2!+3*3!+4*4!+.....+2012*2012!
  =(2-1)*1!+(3-1)*2!+(4-1)*3!+.....+(2012-1)*2011!+(2013-1)*2012!
  =2!-1!+3!-2!+4!-3!+.....+2012!-2011!+2013!-2012!
  =2013!-1!
• 10 years agoHelpfull: Yes(10) No(0)