What number is obtained by adding the units digits of 734^98 and 347^81? Pick one.
A) 10 B) 11 C) 12 D) 13 E) 14
The units digit of 734^98 is 6 because 4 raised to the power of an even integer ends in 6.   The units digit of 347^81 is 7 because powers of 7 end in 7, 9, 3 or 1 cyclically. Since 81 is in the form 4n+1, the units digit is 7.   Then   6+7= 
<gadget id="calculator">  6+7</gadget>
<output>13</output>
13.   The answer is 13.
<result>D</result>
What number is obtained by adding the units digits of 734^98 and 347^81?