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Re: In a set of numbers from 100 to 1000 inclusive, how many integers are [#permalink]
Can someone tell my why we multiply 4*8*9, whats the logic behind multiplying versus another approach?

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Ali
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Re: In a set of numbers from 100 to 1000 inclusive, how many integers are [#permalink]
x-ALI-x wrote:
Can someone tell my why we multiply 4*8*9, whats the logic behind multiplying versus another approach?

Thanks,
Ali


we need to find odd numbers without digit 5 from 100 to 1000 (i.e same as odd numbers without digit 5 from 100 to 999)

let say number= XYZ
Z= units digit
Y= tenths digit
X= Hundredth's digit

For any 3 digit number to be odd, Unit digit must be odd
So Z can be filled with 1,3,7,9 (we are exlcuding digit 5) = 4 ways.
Y can be filled with 0,1,2,3,4,6,7,8,9 (we are ecluding digit 5) = 9 ways
X can be filled with 1,2,3,4,6,7,8,9 (we are exlcuding digits 0 and 5 .. ) = 8 ways

No of ways= 4*9*8= 288
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Re: In a set of numbers from 100 to 1000 inclusive, how many integers are [#permalink]
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Re: In a set of numbers from 100 to 1000 inclusive, how many integers are [#permalink]
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