Odd number of odd digits

[nelsonling]

Hi need some help please;

How many whole numbers in the set 1,2,3,.....,99999 have an odd number of odd digits ?

(A) 49 999 (B) 50 000 (C) 45 000 (D) 55 554 (E) 55 555

 

[Deleted member 4993]

Hi need some help please;

How many whole numbers in the set 1,2,3,.....,99999 have an odd number of odd digits ?

(A) 49 999 (B) 50 000 (C) 45 000 (D) 55 554 (E) 55 555

You have posted several problems - without showing any work.

Unless you show some work - we don't know where to begin to help you.

Pklease show some work - or share your thoughts regarding possible ways to attack the problem.

 

[stapel]

How many whole numbers in the set 1,2,3,.....,99999 have an odd number of odd digits ?

You've posted some much-more-difficult exercises elsewhere. (Granted, you were provided with the complete worked solution on all of those, but you're not here to just copy down answers, right? :wink: ) So you should be well able at least to get started on this question, showing us your work and reasoning thus far.

Please be specific. Thank you!

Eliz.

 

[nelsonling]

Hi need some help please;

How many whole numbers in the set 1,2,3,.....,99999 have an odd number of odd digits ?

(A) 49 999 (B) 50 000 (C) 45 000 (D) 55 554 (E) 55 555

You have posted several problems - without showing any work.

Unless you show some work - we don't know where to begin to help you.

Pklease show some work - or share your thoughts regarding possible ways to attack the problem.

Yes, i had tried doing it in this way but could not get the answer, probably i had interpreted the quesion wrongly;

basically, i did it this way;
Odd number of odd digits
1 to 10 ---- there is 5 odd number of odd digits (1, 3,5,7 &9)
10 to 99 ---- this are not counted as they are even digits.
100 to 999 --- there are 450 odd number of odd digits
1000 to 9999 ---- not counted
10000 to 99999 ----- there are 45000 odd number of odd digits
So, in total there are 5 + 450 + 45000 = 45455 ???

:?: :?:

 

[Denis]

10 to 99 ---- this are not counted as they are even digits.

10 has 1 odd digit: 1 ; so it counts
11 has 2 odd digits: 1 and 1 ; so it does not count
Remember that digits are 0,1,2,3,4,5,6,7,8,9 : 10 to 99 are NOT digits.