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Question 1120022: How many numbers can be formed using only odd digits not more than 1 time each digit?
Found 2 solutions by solver91311, ikleyn:
Answer by solver91311(24713)   (Show Source):
You can put this solution on YOUR website!
Since there are only 5 odd digits, 1, 3, 5, 7, and 9. The largest possible number that can be formed without duplication of digits is a 5-digit number.
Given five different digits, there are exactly 5 different single digit numbers. Then there are 5 times 4 two-digit numbers, 5 times 4 times 3 three-digit numbers, 5 times 4 times 3 times 2 four-digit numbers, and finally 5 times 4 times 3 times 2 times 1 five-digit numbers.
5 X 4 X 3 X 2 X 1
+ 5 X 4 X 3 X 2
+ 5 X 4 X 3
+ 5 X 4
+ 5
Just do the arithmetic
John
My calculator said it, I believe it, that settles it
Answer by ikleyn(52874)  (Show Source):
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