If two digit integer M and N are positive and have same digits, but in reverse order, which of the
following cannot be the sum of M and N.
a) 181
b) 165
c) 121
d) 99
e) 44

• A) 181
  M = 10x+y ; N = 10y+x so M + N = 11x + 11y = multiple of 11.
  181 is the only option which is not a multiple of 11
• 14 years agoHelpfull: Yes(2) No(0)
• The correct option will be 181
  M=10x+y
  N=10y+x
  M+N=11x+11y=11(x+y)=divisible by 11
  but except 181 all the numbers are divisible by 11.
  so,my ans is 181.
  thank you.
  
• 14 years agoHelpfull: Yes(1) No(0)
• a) 181
• 14 years agoHelpfull: Yes(0) No(0)
• The numbers are 10x+y and 10y+x. Adding, we get 11(x+y). i.e., the sum is a multiple of 11, which all except 181 are. So, the sum cannot be 181
• 14 years agoHelpfull: Yes(0) No(0)
• let the 2 digits be x and y
  so, the sum of the 2 nos. will be : (10x+y)+(10y+x) = 11(x+y)
  so, the answer has to be a multiple of 11...so (a)181 c..is the answer
• 14 years agoHelpfull: Yes(0) No(0)
• a)181 as sum should be divisible by 11
• 14 years agoHelpfull: Yes(0) No(0)