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

• when ever we revert a 6 to 9, which is in untits position its value will increse by 3, like that in units place there are 10 six's . . so sum will increase by 30
  If the six in 10's place reverts to 9, its value will increase by 30, hence like that in 10's position we have 10 six's the sum will increase by 300
  
  
  so total change in the sum = 330
• 13 years agoHelpfull: Yes(53) No(6)
• c) 330
  6,16,26,36,46,56,60,61,62,63,64,65,66,67,68,69,76,86,96 will respectively change to 9,19,29,39,49,59,90,91,92,93,94,95,99,97,98,99,79,89,99.
  
  Therefore change (increase) = 3*9 + 30*9 + 33 = 27 + 270 + 33 = 330
• 13 years agoHelpfull: Yes(17) No(9)
• b)330
  9*3+9*30+33=330
• 13 years agoHelpfull: Yes(4) No(2)
• 9*3+9*30+33=330
• 10 years agoHelpfull: Yes(1) No(3)
• 3+(9*3)+(9*30)-30=300
• 10 years agoHelpfull: Yes(1) No(4)
• For the 6 at the unit place:
  When the digits are changed to 9, each value will increase by 3. Since there are 10 such numbers, so total increase = 10 * 3 = 30
  For the 6 at 10’s place:
  When the digits are changed to 9, each value will increase by 30. Since there are 10 such numbers, so total increase = 10 * 30 = 300
  So the total increase will be 30 + 300 = 330
• 6 years agoHelpfull: Yes(0) No(0)
• 3*9 + 30*9 + 33=330
• 5 years agoHelpfull: Yes(0) No(0)