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    jess has a 4 digit password for her mobile phone. each digit can be between 0 and 9 inclusive.Jess would like to choose an even umber.the code can start with a zero.How many possible ways are possible now? answer is 5000 btw !
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    10*10*10*10 / 2
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    (Original post by iow16)
    10*10*10*10 / 2
    why is there a 2 tho????
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    (Original post by shaaruka)
    why is there a 2 tho????
    Even eliminates half the possible numbers.
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    0-9 digits has 10 different possibilities
    There are 4 digits, so you do:

    10*10*10*10 = 10,000

    Now, the number has to be even. If there were 10 numbers we could split them into even and odd
    0,2,4,6,8 - EVEN
    1,3,5,7,9 - ODD

    There are 5 even and 5 odd. This means that 5/10, or a 1/2 of the numbers will be even. So we do:

    10,000 / 2 = 5,000
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    Only half the numbers between 0 and 10000 are even.
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