Manipal Engineering Manipal Engineering Solved Paper-2008

  • question_answer
    The number of positive divisors of 252 is

    A)  9                                            

    B)  5   

    C)  18                         

    D)         10

    Correct Answer: C

    Solution :

    We know that, if\[a=p_{1}^{{{\alpha }_{1}}}\cdot p_{2}^{{{\alpha }_{2}}}\] Then, the total number of positive divisors of\[a\] is                 \[T(a)=({{\alpha }_{1}}+1)({{\alpha }_{2}}+1)....\] Given,   \[252={{2}^{2}}\times {{3}^{2}}\times {{7}^{1}}\] Here,     \[{{\alpha }_{1}}=2,\,\,{{\alpha }_{2}}=2,\,\,{{\alpha }_{3}}=1\] \[\therefore \]  \[T(a)=(2+1)(2+1)(2+1)\]                 \[=3\cdot 3\cdot 2\]                 \[=18\]


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