Question 565592: how many counting numbers between 100 and 1000 have at least one 2 as a digit?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! how many counting numbers between 100 and 1000 have at least one 2 as a digit?
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# with at least one "2" = (total #'s) - (# with no "2")
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total #'s = 1000-100 = 900 + 1 = 901
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1st digit: 8 ways
2nd digit: 9 ways
3rd digit: 9 ways
If "1000" is included, add 1 to the number without a "2".
# with no "2" = 8*9*9 = 648 +1 = 649
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P(at least one "2") = 1 - [649/901] = 0.2797
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Cheers,
Stan H.
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