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<p>Because you can use your logic to recognize a problem and apply a VERY simple and elegant solution that works every time on the SAT. </p>
<p>By the way, when the problem appears on the SAT on a multiple choice, do you realize you CAN answer it with logic in 2 seconds? I could also tell you that the answer is always B, but that would be too darn much logic for one day.</p>
<p>Anyway, learn the darn formula and be happy you did! </p>