w, q, and r are positive integers. If w, q, and r are assembled into the six-digit number wqrwqr, which one of the following must be a factor of wqrwqr?  Choose the correct choice from the following choices: A) 23 B) 19 C) 17 D) 7 E) none of the above
One short way -   wqrwqr = 1000wqr + wqr = (1000+1)= 
<gadget id="calculator">(1000+1)</gadget>
<output>1_001</output>
1001wqr   Therefore any factor of 1001 is a factor of wqrwqr   7 is a factor of 1001   So 7
<result>D</result>
w, q, and r are positive integers. If w, q, and r are assembled into the six-digit number wqrwqr, which one of the following must be a factor of wqrwqr?