CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2005

  • question_answer
    When \[{{2}^{301}}\] is divided by 5, the least positive remainder is :

    A)  4                                            

    B)  8

    C)  2                                            

    D)  6

    Correct Answer: C

    Solution :

    Since \[{{2}^{1}}=2,\,\,{{2}^{2}}=4,\,{{2}^{3}}=8,\,{{2}^{4}}=16,\,{{2}^{5}}=32\] It is clear that unit place is repeated after every four power                 then, \[{{2}^{301}}={{({{2}^{4}})}^{75}}.2\]                 \[={{\text{(}16\text{)}}^{75}}.2\] \[\therefore \] digit at unit place in \[{{(16)}^{75}}\] is 6 \[\therefore \] Digit at units place in \[{{2}^{301}}=\] digit at units place in (6). 2                 = 2 Hence die remainder, when \[{{2}^{301}}\] is divided by 5, is 2.


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