Q. The units digit of the sum of the first 97 positive integers (that is 1 + 2 + 3 + ... + 97 ) is

• 433
  the sum of all units place of 1 to 9 = 45
  so,upto 100 numbers is 45*10=450
  then
  we havw up to 97 only.....so minus of 8and9 gives 450-17=433
• 10 years agoHelpfull: Yes(25) No(4)
• ans is 3.....
  sum of n natural numbers is (n(n+1))/2.so (97*98)/2=97*49...so 9*7=63....so unit digit is 3
• 10 years agoHelpfull: Yes(18) No(3)
• i guess answer is 4753 is it right ?
• 10 years agoHelpfull: Yes(6) No(6)
• 1 + 2 + 3 + ... + 97
  then by adding all unit place digits we get 433
  then in units place 3 is present
• 10 years agoHelpfull: Yes(6) No(2)
• sorry, I didnt read question carefully,units digit =3 because sum=4753
  ans=3
• 10 years agoHelpfull: Yes(4) No(2)
• the sum of positive integers=n*(n=1)/2
  Here, n=97
  Sum=4753
• 10 years agoHelpfull: Yes(2) No(2)
• s=n*(n+1)/2
  here, n=97
  so, s=4753
  unit digit is 3
• 10 years agoHelpfull: Yes(2) No(1)
• sum of the seires =n/2[2a+(n-1)d] ,here n=97 a=1 and d=1 thus value obtained will be 4753 from the formula,here unit digit is 3
• 10 years agoHelpfull: Yes(1) No(0)
• 4753 is rite ans
• 10 years agoHelpfull: Yes(1) No(0)
• 97/2*(1+97)=4753
  unit digit=3
• 10 years agoHelpfull: Yes(1) No(1)
• (97*(97+1))/2
  4753
• 10 years agoHelpfull: Yes(0) No(1)
• sum=(n*(n+1))/2.
  here n=97 s0 n*(n+1)=9506
  so sum=4753
  units digit=3
• 10 years agoHelpfull: Yes(0) No(0)
• 3 is the ans
• 10 years agoHelpfull: Yes(0) No(1)
• 3 because 9*7 is 63.
• 10 years agoHelpfull: Yes(0) No(2)
• sum of 1-10 gives 45 so unit digit is 5,then 11-20(count for 1-10) unit digit is 5
  so up to 8 ie 81-90 it is 45 so unit place is 5.so summing up its 8*5=40 so unit place is 0.then 91 to 97 its 28,add unit places u get 8 ans.
• 10 years agoHelpfull: Yes(0) No(2)
• 5
  1+2+3+4+5+6+7+8+9+10
• 10 years agoHelpfull: Yes(0) No(0)
• 450-17=433
• 10 years agoHelpfull: Yes(0) No(0)
• unit digit is 3..
• 10 years agoHelpfull: Yes(0) No(1)
• The Answer is 3
• 10 years agoHelpfull: Yes(0) No(0)
• answer is 8.
  sum of 1 to 9 = 45
  to 90 unit digit will be 0(5+5=10)
  sum of 1 to 7 = 28
  so, answer is 8.
• 10 years agoHelpfull: Yes(0) No(0)
• n(n+1)/2=97(97+1)/2=97(49)=3
• 9 years agoHelpfull: Yes(0) No(1)
• since the given problem is in A.P
  common diff=1,and total no.of terms =97
  so ,sum is =97(1+97)/2 =97*49
  by using remainder method,(97*49)/10 =(7*9)/10 =3
  so unit digit of the sum is = 3.
  
  
• 9 years agoHelpfull: Yes(0) No(0)