Ayush
Lv 5
Ayush asked in Science & MathematicsMathematics · 8 years ago

Permutation problem..Number of numbers from 1 to 2010 having at least one digit as 4 are?

Number of numbers from 1 to 2010 having at least one digit as 4 are??

The answer is 543 but i cant figure it out

1 Answer

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  • M3
    Lv 7
    8 years ago
    Favorite Answer

    find out, instead NO 4's in the # first

    1 digit #: 8

    2 digit #: 8*9 = 72

    3 digit #: 8*9*9 = 648

    1000-1999: 9*9*9 = 729

    2000-2010: just count 10

    total #s w/o 4 = 1467

    ans: 2010 - 1467 = 543 <------ qed

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