(6^2007-6^2006)/30

$$\\ \frac{6^{2007}-6^{2006}}{30} = \frac{6^{2006}\times 6-6^{2006}}{30} = \frac{6^{2006}(6-1)}{30} = \frac{6^{2006}\times 5}{30}=\frac{6^{2006}}{6}=6^{2005}$$

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