pnc

how many 4digit numbers are there whose sum of the digits is odd?

6 Answers

71
Vivek @ Born this Way ·

Try to use the parity. ie., O+O = E , O+E = O and E+E=E .

So take different cases, first include one Even and so on.

1
funkygp ·

yes i did it in the same way.
i was getting 13140 ,could anyone confirm or just solve it once...........

1057
Ketan Chandak ·

@funkygp...there ain't exist 13140 4 digit numbers !!!! only 9000 4 digit numbers are there....and i think the answer shud be 4500...

1
funkygp ·

oops!!!!!

i will try to calc again

262
Aditya Bhutra ·

Hint : the sum of digits is odd or even depends only on the choice of last digit

Ans: 4500

3
h4hemang ·

hmmm.
aditya is correct.
the pattern is very cool.
OEOEOEOEOE. for the numbers from 1000 to 1009.
then from 1010 to 1019, it is
EOEOEOEO.
so it flips. :)

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