Mr. A took the sum of natural numbers. By mistake he added a number twice and find the sum to be 1000. Find the repeated number.
1)20 2)15 3)10 4)18

• sum of natural number =n(n+1)/2
  so if we take 44 as a number then =44(44+1)/2 =44*45/2 =1980/2 =990
  so we have to add 10 to make it 1000 ....So 10 is repeated.
• 4 years agoHelpfull: Yes(3) No(1)
• 3) 10
  Sum of first 45 natural no is 990
  Hence 10 ia calculated twice in order he gets 1000 as sum
• 4 years agoHelpfull: Yes(1) No(2)
• 3) 10
  Sum of first 44 natural no is 990
  Hence 10 is calculated twice.
• 4 years agoHelpfull: Yes(1) No(0)
• option 3) 10
• 4 years agoHelpfull: Yes(0) No(2)