JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2009

  • question_answer
        The exponent of 12 in 100 is

    A)  48                                         

    B)  49

    C)  96                                         

    D)  None of these

    Correct Answer: A

    Solution :

                     We have, \[12={{2}^{2}}\times 3=2\times 2\times 3\] Now, \[a={{E}_{2}}(100!)=\left[ \frac{100}{2} \right]+\left[ \frac{100}{{{2}^{2}}} \right]\]                 \[+\left[ \frac{100}{{{2}^{3}}} \right]+\left[ \frac{100}{{{2}^{4}}} \right]+\left[ \frac{100}{{{2}^{5}}} \right]+\left[ \frac{100}{{{2}^{6}}} \right]\] \[=50+25+12+6+3+1=97\] \[b={{E}_{3}}(100!)=\left[ \frac{100}{3} \right]+\left[ \frac{100}{{{3}^{2}}} \right]\]                                                 \[+\left[ \frac{100}{{{3}^{3}}} \right]+\left[ \frac{100}{{{3}^{4}}} \right]\] \[=33+11+3+1=48\] \[\therefore \]  \[{{E}_{12}}(100!)=\min (a,b)\] Hence, \[{{E}_{12}}(100!)=48\]


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