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Math Help - what is the common multiple ..

  1. #1
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    what is the common multiple ..

    of 20 and 36
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  2. #2
    A riddle wrapped in an enigma
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    Quote Originally Posted by ckica View Post
    of 20 and 36
    Hi ckica,

    I guess you're looking for the least common multiple, right?

    Factor each value using prime factors:

    20=2^2 \cdot 5

    36=2^2 \cdot 3^2

    Now multiply all the different factors using their greatest exponent:

    LCM=2^2 \cdot 3^2 \cdot 5=180
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  3. #3
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    Oh thanks you so much so the answer is 180?
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    A riddle wrapped in an enigma
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    Quote Originally Posted by ckica View Post
    Oh thanks you so much so the answer is 180?
    It is if you're looking for the least common multiple, which I assumed.

    List the multiples of 20 and 80. You see that 180 is the first multiple common to both. There is an infinite numbers of common multiples, but 180 is the least common multiple (LCM).

    20, 40, 60, 80, 100, 120, 140, 160, 180

    36, 72, 108, 144, 180
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