2. Sample Papers
  3. Railways
  4. Quantitative Aptitude
  5. Number System and its Operations

Railways Quantitative Aptitude Number System and its Operations Sample Paper Number System Sample Test Paper-1

  • question_answer
    Unit place digit in the product of first 40 odd natural number is

    A)  6        

    B)         0       

    C)  5                    

    D)  8

    Correct Answer: C

    Solution :

    [c] Product of first 40 odd natural \[=1\cdot 3\cdot 5\cdot 7\cdot 9.\,\,......\,\,79.\] \[=15\cdot (7\cdot 9\cdot \,\,.......\,\,79)\] =15 \[\times \] an old number So there will be 5 at unit place. So answer is 5.


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