If the two-digit integers M and N are positive and have the same digits, but in reverse order, which of the following CANNOT be the sum of M and N?  Choose the correct choice from the following options:
A) 181 B) 165 C) 121 D) 99 E) 44
M=10x+y   N=10y+x   M+N=11x+11y=11(x+y)   In other words the answer is a multiple of 11.   Now the question becomes " which of the following is NOT a multiple of 11?"   181nswer -181   181NSWER:181
<result>A</result>
If the two-digit integers M and N are positive and have the same digits, but in reverse order, which of the following CANNOT be the sum of M and N?