Q. The sum of (1*1!)+(2*2!)+(3*3!)+....+(1201*1201!)

• 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
  .....
  ........
  similarly
  (1*1!)+(2*2!)+(3*3!)+....+(1201*1201!)=(1202!-1)
  
• 11 years agoHelpfull: Yes(50) No(0)
• (1*1!)+(2*2!)+.....+(1201*1201!) can be written as (2!-1!)+(3!-2!)+(4!-3!)+....+(1202!-1201!).so, answer is 1202!-1
• 11 years agoHelpfull: Yes(3) No(0)
• we can write series like this (2!-1!)+(3!-2!)+(4!-3!)+....+(1202!-1201!)
  now
  all fro 2! to 1201!are cancel with each other
  1202!-1! is left so
  = 1202!-1 ans...
• 11 years agoHelpfull: Yes(1) No(0)