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How many 7digit numbers are having sum of digits ODD?
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13 Oct 2018, 08:59
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Re: How many 7digit numbers are having sum of digits ODD?
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13 Oct 2018, 09:13
smallest 7 digit number=1000000 greatest=9999999. total 7 digit number=99999991000000+1=90000000 So now out of 9000000,half have sum as odd and half has sum as even.So 4500000 are having sum as odd. so C is the answer




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Re: How many 7digit numbers are having sum of digits ODD?
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13 Oct 2018, 09:05
According to me the answer should be (C). Please find my solution attached. Regards, GLadi
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Re: How many 7digit numbers are having sum of digits ODD?
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13 Oct 2018, 09:13
How many 7digit numbers are having sum of digits ODD? A) 3505000 B) 4350200 C) 4500000 D) 4520500 E) 5502000 OA: C a 7 digit number : _ _ _ _ _ _ 7th' first digit : {1,2,3,4,5,6,7,8,9}  9 values 2nd,3rd,4th,5th,6th : {0,1,2,3,4,5,6,7,8,9}  10 values the 7th digit takes set of { 1,3,5,7,9}  5 values , all odd numbers
total no of values you can get with these : 9*(10^5)*5 = 4500000



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Re: How many 7digit numbers are having sum of digits ODD?
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13 Oct 2018, 09:21
How many 7digit numbers are having sum of digits ODD? A) 3505000 B) 4350200 C) 4500000 D) 4520500 E) 5502000 Answer B,C ,D &E: 5,9,7,3



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Re: How many 7digit numbers are having sum of digits ODD?
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Updated on: 13 Oct 2018, 11:04
Total number of 7 digit integers 9999999999999=9,000,000 Half of them have even sum and other odd sum. ( can ve verified in any consecutive series if even number of terms say... 11,12,13, 14 ===> 4 terms ....2 even sum & 2 odd sum again 11,12,13......20 ==>10 terms ....5 even sum & 5 odd sum) Hence, Odd sum = 9,000,000/2= 4,500,000 Ans C.
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Please let me know if I am going in wrong direction. Thanks in appreciation.
Originally posted by u1983 on 13 Oct 2018, 09:22.
Last edited by u1983 on 13 Oct 2018, 11:04, edited 1 time in total.



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Re: How many 7digit numbers are having sum of digits ODD?
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13 Oct 2018, 10:01
total count of 7 digit number =99999991000000+1=9000000...so every alternate number in the set will have a sum even or odd,so half the 7 digit numbers would have odd sum hence 9000000/2=4500000.Hence answer C



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Re: How many 7digit numbers are having sum of digits ODD?
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28 Oct 2018, 02:40
7 digit numbers are from 1000000 to 9999999.
First we need to find the total number of terms from 1000000 to 9999999.
(Last term  first term) +1 => (9999999  1000000) + 1 => 8999999 + 1 => 9000000
We know there are 5 odd integers and 5 even integers in every 10 numbers.
So we divide 9000000/2 = 4500000
Hence C




Re: How many 7digit numbers are having sum of digits ODD? &nbs
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28 Oct 2018, 02:40






