A two digit no is 18 less than square of the sum of its digit.how many such no are there?

• well got something wrong there...
  ans: 2
  63=(6+3)^2-18=81-18
  82=(8+2)^2-18=100-18
• 11 years agoHelpfull: Yes(52) No(8)
• 2 such digits are possible.
  
  soln:
  2 digit squares are : 16,25,36,49,64,81 and 100 will also b counted as 100-18=82 which is a 2 digit number.
  
  now use hit and try method using derived formula 10x+y + 18 = ( x + y)^2
  
  16,25 are not possible then comes 36,49,64 the are also not the required digits.
  next comes 81 : (8+1)^2= 81 also 81-18=63 where (6+3)^2=81 so, 63 is the one.
  Similarly for 100 : (10+0)^2=100 also 100-18=82 where (8+2)^=100 so, 82 is second.
  
• 11 years agoHelpfull: Yes(14) No(1)
• only 1
  ans is 63
  bcoz 6^2+3^2=45
  63-45=18
• 11 years agoHelpfull: Yes(13) No(20)
• @sandy,@ujjwal- how did u get the ans..i mean plz share ur approach as well..
• 11 years agoHelpfull: Yes(9) No(0)
• ans: 2
  63=(8+1)^2-18=81-18
  82=(8+2)^2-18=100-18
• 11 years agoHelpfull: Yes(6) No(2)
• ans is 63
  bcoz 6^2+3^2=45
  63-45=18
• 11 years agoHelpfull: Yes(4) No(9)
• 2 no's are possible that are 63 and 82
• 11 years agoHelpfull: Yes(4) No(1)
• i think 61
• 11 years agoHelpfull: Yes(1) No(3)
• how did you came to knw abt these 2 nos??
• 11 years agoHelpfull: Yes(1) No(0)
• 63 ANS
  63+18=(6+3)^2
  
• 11 years agoHelpfull: Yes(0) No(0)
• yes only one number that is 56
  
• 11 years agoHelpfull: Yes(0) No(0)
• 82 ....100-18=82
  
• 11 years agoHelpfull: Yes(0) No(0)
• 82 is not possible because it doesn't fulfilling the definition. we want the difference of no. and the sum of the square of the digit of that no.
  In case of 82 the sum of the square of it's digit is 68 i.e. (64+4=68). now according to definition
  83-68=14
  That is wrong, It should have been 18.
  Hence, 63 is the only no. for this question.
• 11 years agoHelpfull: Yes(0) No(6)
• 99-18=81,8+1^2-18=63
  63-18=45,4+5^2-18=63
  45-18=27,2+4^2-18=63
  27-18=9,9^2-18=63
  there are a total of 4 ,2 digit nos.
• 11 years agoHelpfull: Yes(0) No(1)
• 63, and 82 are those two number !!!
• 11 years agoHelpfull: Yes(0) No(0)
• Ans is 4.......
  12,13,21,31 are the two digit no.s, these sum of individal digits square is less than the 18
  (1+2)^2=9
• 11 years agoHelpfull: Yes(0) No(0)