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Math Help - [SOLVED] Permutation and Combination Question 2

  1. #1
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    [SOLVED] Permutation and Combination Question 2

    How many four-digit number greater than 5,000 can be formed from the digits 0, 1, 2, 3, 4, 5 if all digit may be repeated?

    I get 215, but the answer sheet say it's 216. I don't understand. Can someone please explain?

    The 1st digit must be 5 or greater, so, there's only 1 choice.
    the 2nd, 3rd, 4th position can be any digit, so each for 6 choice.

    So, 1 * 6 * 6 * 6 = 216
    But we have to minus away 5,000 right. it's not greater than 5,000.
    So 216 - 1 = 215
    Am I not right?
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  2. #2
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    Quote Originally Posted by azuki View Post
    How many four-digit number greater than 5,000 can be formed from the digits 0, 1, 2, 3, 4, 5 if all digit may be repeated?

    I get 215, but the answer sheet say it's 216. I don't understand. Can someone please explain?

    The 1st digit must be 5 or greater, so, there's only 1 choice.
    the 2nd, 3rd, 4th position can be any digit, so each for 6 choice.

    So, 1 * 6 * 6 * 6 = 216
    But we have to minus away 5,000 right. it's not greater than 5,000.
    So 216 - 1 = 215
    Am I not right?
    Right.
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