What 5-digit Number Has The Following Features:

What 5-digit Number Has The Following Features:


  • Posted by  Downloadmela 
    10 Feb, 2012

    What 5-digit number has the following features:

    If we put the numeral 1 at the beginning, we get a number three times smaller than if we put the numeral 1 at the end of the number.


    Solution
    Using an easy equation:

    3(100000 + x) = 10x+1

    (Why? Well, adding 100000 puts a 1 at the front of a five-digit number, and multiplying by 10 and adding 1 puts a 1 at the end of a number)

    Solving this gives:

    10x+1 = 3(100000 + x)
    10x+1 = 300000 + 3x
    10x = 299999 + 3x
    7x = 299999
    x= 299999/7 = 42857

    The answer is 42857.

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