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Railways Quantitative Aptitude Basic Calculations Sample Paper Square Roots & Cube Roots Sample Test Paper-5

  • question_answer
    The least 6 digit number which is perfect square is

    A)  100000

    B)  100144  

    C)  100489

    D)  100225

    Correct Answer: C

    Solution :

    [c] Least six digit number is 100000, which is not a perfect square because it has odd number of zeroes. First let us extract the square number hidden in it.
    316
    3 10 00 00   9
    61 100   61
    626   3900   3756
         154
    \[\therefore \] We find that \[100000>{{(316)}^{2}}\] by 154      Next square number \[{{(317)}^{2}}>100000\] \[\therefore \] \[{{(316)}^{2}}<100000<{{(317)}^{2}}\] \[\therefore \] If we add \[{{(317)}^{2}}-100000=489\] to 100000     We get least six digit perfect sq. no.  \[\therefore \] Least four digit perfect square no. is 100489.


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