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Math Help - Base 5

  1. #1
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    Base 5

    Does 124(base 5) represent an odd number? How can you determine whether a number is odd by looking at its base-five representation?

    Any takers?
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  2. #2
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    Quote Originally Posted by t-lee View Post
    Does 124(base 5) represent an odd number? How can you determine whether a number is odd by looking at its base-five representation?

    Any takers?
    (124)_5
    Is,
    1\cdot 5^2 +2\cdot 5^1+4\cdot 1
    Is that even or odd?
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  3. #3
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    Hello, t-lee!

    Does 124_5 represent an odd number? . . . no

    How can you determine whether a number is odd by looking at its base-five representation?

    Since the base is an odd number, it could be tricky.

    But there is a simple rule:
    . . Even number of odd digits: even
    . . .Odd number of odd digits: odd

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  4. #4
    MHF Contributor Quick's Avatar
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    Quote Originally Posted by Soroban View Post

    Since the base is an odd number, it could be tricky.

    But there is a simple rule:
    . . Even number of odd digits: even
    . . .Odd number of odd digits: odd

    there is an odd number of odd digits in 124...
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  5. #5
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Quick View Post
    there is an odd number of odd digits in 124...
    Yes, which means that 124_5 is odd which, in fact, it is. Don't let that 4 on the end fool you. What TPH was trying to say is that
    1 \cdot 5^2 is odd
    2 \cdot 5^1 is even
    4 \cdot 5^0 is even

    odd + even + even = odd.

    -Dan
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