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