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Geometry-Sequences with unlimited repeated values

  1. May 3, 2006 #1
    Here is the question I cannot get it....

    In a series of license plates, the first three symbols are any of the 26 letters in the alphabet and the last three are any of the 10 digits from 0 to 9.

    How many plates can be formed in which at least one symbol is repeated?

    --------I know that 26^3x10^3 is the total possible combinations.
    I thought that you would do this: (26^3-25^3)x(10^3-9^3)
  2. jcsd
  3. May 4, 2006 #2
    You want to know how many plates can be formed with at least one repeated symbol. Have you considered the negation? I.e. how many plates can be formed with at most zero repeated symbols?
  4. May 4, 2006 #3


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    I think the expression "unlimited repeated values" simply means that you can use any letter or digit more than once so your first expression would be correct.
  5. May 4, 2006 #4


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    Practical caveat. NY current plate has four digits (not three), but the first digit cannot be 0. In addition the letters I and O appear to have been omitted deliberately, looking too much like 1 and 0.
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