consider a two digit number "ab". square the number and divide the resultant by half of the numer. then add 18 in the resultant. and then divide by 2 the resultant. How many numbers are possible that it reversing the digit ex. "ba".

option:
A. 7
B. 8
C. 9
D. one more option I don't remember

• If the number is ab. Then it will be 10a+b.
  Square it => (10a+b)^2
  Divide by half the number => [(10a+b)^2] / [(10a+b)/2] => 2(10a+b)
  Add 18 => 2(10a+b) + 18
  Divide by 2 => (10a+b) + 9
  
  This is equal to reverse of the number so => 10b+a
  Equate them-
  10a+b+9 = 10b+a
  9a-9b = -9
  b - a = 1
  
  So we see the condition is :- (one's digit) - (tens digit) = 1
  So there are 8 possibilities- 12, 23, 34, 45, 56, 67, 78, 89.
• 7 years agoHelpfull: Yes(36) No(5)
• simple....
  1. x=the number
  2. x^2 and divide it by x/2
  3. we get 2x
  4. add 18 we get 2x+18
  5. divide by 2 we get x+9
  6. now use hit and trial
  7. 12+9=21
  23+9=32
  34+9=43
  .
  .
  .
  89+9=98
  8. so total possible number are=8
• 7 years agoHelpfull: Yes(3) No(6)
• B.....My answer is my explaination
• 7 years agoHelpfull: Yes(1) No(8)
• ans: 9
  
  ab+9=ba
  
  01+9=10
  12+9=21
  23+9=32
  34+9=43
  .
  .
  89+9=98
• 7 years agoHelpfull: Yes(1) No(4)
• D...................NO EXPLANATION
• 7 years agoHelpfull: Yes(0) No(6)
• Answer: 8
  ((ab)^2/ab + 18)/ 2 = ab + 9
  now ab + 9 = ba
  ab = 10a + b
  ba = 10b + a
  10a + b + 9 = 10b + a
  9a - 9b + 9 = 0
  b = a + 1
  now assuming base 10 number system is used
  so a can be [1, 8] not including 0 and 9 so to satisfy above conditions and a cant be 0 as to make it two digit number
  so a can assume only 8 possible values between 0 to 8
• 7 years agoHelpfull: Yes(0) No(2)
• B.
  possible numbers are
  12,23,34,45,56,67,78,89
• 7 years agoHelpfull: Yes(0) No(1)
• anwer will be 8 as we cannot consider 01+9=10 coz den 01 will not be 2 digit number. read the 1st sentence its written ab is 2 digit no.
• 6 years agoHelpfull: Yes(0) No(0)