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