SOLUTION: What is the number of 3 digit numbers, with repeats, that are multiples of 5 and less than 600 that can be formed from the digits 1, 3, 5, 7, and 9?

Algebra ->  Permutations -> SOLUTION: What is the number of 3 digit numbers, with repeats, that are multiples of 5 and less than 600 that can be formed from the digits 1, 3, 5, 7, and 9?      Log On


   

Question 1117622: What is the number of 3 digit numbers, with repeats, that are multiples of 5 and less than
600 that can be formed from the digits 1, 3, 5, 7, and 9?
Found 2 solutions by solver91311, greenestamps:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


  5
 15  115  315 515
 35  135   |   |
 55  155   V   V
 75  175
 95  195


6 + 5 + 5 + 5 = 21

Yep, Greenstamps is right. My answer is 6 too many. Comes from answering questions at 11:30 at night.

John

My calculator said it, I believe it, that settles it

Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


Note the other tutor counted some numbers that are 2 digits instead of 3....

(1) There is only one choice (5) for the 3rd digit, since it must be divisible by 5.
(2) There are only 3 choices (1, 3, 5) for the first digit, since the number must be less than 600.
(3) The middle digit can be any of the 5 given digits.

So the number of 3-digit numbers less than 600 that are multiples of 5 is

(1)*(3)*(5) = 15