If all 6’s get inverted and become 9’s , by how much will the sum of all nos. between 1 and 100 both inclusive change?

a) 300 b) 330 c) 333 d) none of these

• Ans:- 330
  In the series of 60,61,62...69 ...when they all inverted there will be a difference of 30
  so 30*10=300...but when 66 is inverted it become 99 so there will be difference of 33 ..thus we will add 3 in 300...thus it become 303
  
  Now in all other there will be difference of 3 ..so 3*9=27..(as we are done with 60 series thus 9)
  
  so 303+27=330
• 10 years agoHelpfull: Yes(4) No(1)
• ans is 330
• 11 years agoHelpfull: Yes(1) No(0)
• from 1-10,actual sum and new sum differs by 3 as 6 is now replaced with 9.
  10-20 difference is 3
  in this way from 1-59,70-100 there will be a total difference of 3*10=30(1-10,11-20,21-30,31-40,41-50,51-59,70-79,80-89,90-99)
  according to question 60is 90,61is 91,so the difference is 30*10=300
  (60-90,61-91,62-92,63-93,64-94,65-95,66-96,67-97,68-98,69-99)
  total =30+300=330
  
• 10 years agoHelpfull: Yes(1) No(2)
• When 6's at unit place is changed to 9, value will increase by 3. There are 10 such numbers.
  
  When 6's at 10's place is changed to 9, value will increase by 30. There are 10 such numbers.
  
  For 6's at unit place : 10 * 3 = 30
  
  For 6's at 10s place : 10 * 30 = 300
  
  So the answer is 30 + 300 = 330
  
  
• 8 years agoHelpfull: Yes(0) No(0)