The average of the two-digit numbers, which remain the same when the digits interchange their positions, is? Options
A) 22
B) 89
C) 55
D) 38
E) 13
Average = (11 + 22 + 33 + 44 + 55 + 66 + 77 + 88 + 99)/9   = [(11 + 99) + (22 + 88) + (33 + 77) + (44 + 66) + 55]/9   = [(4 * 110) + 55]/9 = 495/9= 
<gadget id="calculator">495/9</gadget>
<output>55</output>
55.   Answer:55
<result>C</result>
The average of the two-digit numbers, which remain the same when the digits interchange their positions, is?