If r = 199,999 and s = 991,999, which of the following is the units digit of r^2 + s^2?  Choose the correct choice from the following answers.
A) 0
B) 1
C) 2
D) 8
E) 9
The exponents of 9 cycle between 9 (odd exponents) and 1 (even exponents).   Then the sum of r^2+s^2 will have   1+1= 
<gadget id="calculator">  1+1</gadget>
<output>2</output>
2 as a units digit.   The answer is 2.
<result>C</result>
If r = 199,999 and s = 991,999, which of the following is the units digit of r^2 + s^2?