.9 Find the sum of all the odd numbers starting from 1 and ending at the greatest 4 digit number.




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• 1+3+5+7+........+9999
  from A.P. find tn.
  so tn=5000
  now Sn= n/2(a+l)
  n=5000, a=1, and l= 9999
  slove this ans is 25000000.
• 9 years agoHelpfull: Yes(10) No(2)
• Always remember that sum of first n odd number is always =n^2
  Means n is to power of 2.
  So ,in question the value of n is 9999(largest 4 digit number)
  Therfore,9999^2=99980001
  
• 9 years agoHelpfull: Yes(6) No(3)
• by using formula for the addition of odd numbers= ((l+1)/2)^2
  l=9999(last term)
  =((9999+1)/2)^2
  =25000000 ans
• 9 years agoHelpfull: Yes(4) No(0)
• we knw that greatest 4 digit is 9999
  1+3+5+7+........+9999
  from A.P. find tn.
  so tn=9999
  now Sn= n/2(a+l)
  tn =a+(n-1)d
  from this we get n=5000
  therefore Sn=25000000
• 9 years agoHelpfull: Yes(2) No(0)
• odd numbers starting from 1 and ending at the greatest 4 digit number : 1,3,5.....9999
  Sum of first n odd numbers : n*n = 9999*9999 = 99,980,001
• 9 years agoHelpfull: Yes(1) No(2)