+0

# Help

-1
1160
5
+2096

How many odd five-digit counting numbers can be formed by choosing digits from the set [1,2,3,4,5,6,7]  if digits can be repeated?

Mar 22, 2020

#1
+128845
+4

The 5 digit number will  end  in either  1, 3, 5 or 7

Since  digits  can be repeated we have 7 choices for each of  the 4 leading positions  and 4  choices for the  ending digit

So....the total number of odd five-digit countig numbers  =

7^4  * 4  =

9604

Mar 22, 2020
#2
+36921
+4

A different perspective...just an FYI

7possible numbers      4 out of 7 are odd     75  x  4/7 = 9604  (as Chris calculated)

Mar 22, 2020
#3
+2096
0

Thanks!!!

Mar 22, 2020
#4
+118623
0

Cal has told me that this wasn't actually her question.

The system is sometimes capturing her username and assigning it to guest questions that have just been posted.

I assume she is on shared wifi or something like that.

Anyway she says she is glad it happened this time because she learned a lot from EP and Chris who so kindly answered this question.

Thanks guys

It is so nice to know that we have genuine learners here.   Thanks Cal.

Melody  Mar 24, 2020
#5
+2096
0

Phew! Thanks so much, Melody!!!

CalTheGreat  Mar 25, 2020