Find the value of 1+1x1! + (2 × 2!) + (3 × 3!) + … + (100 × 100!)

• we can write
  1!+1*1!+2*2!+........+100*100!
  now
  3*3!=3(2*2!+1*1!+1!)
  similarly
  sum of before 100*100! is 100*100!
  hence ans=
  100*100!+100*100!=200*100!
  is it right??
• 11 years agoHelpfull: Yes(8) No(1)
• ans is 101!........
  1*1!=2!-1!
  2*2!=3!-2!
  3*3!=$1-3!
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  100*100!=101!-100!
  1+1*1!+2*2!+3*3!.......+100*100!=
  1+2!-1!+3!-2!+4!-3!+.........+101!-100!=1-1!+101!=101!
• 11 years agoHelpfull: Yes(7) No(0)
• 1!+1*1!+2*2!+........+100*100!
  now
  3*3!=3(2*2!+1*1!+1!)
  similarly
  sum of before 100*100! is 100*100!
  hence ans=
  100*100!+100*100!=200*100!
  
• 10 years agoHelpfull: Yes(0) No(0)